The Uncanny Crusade

 	The Eternal Crusader came screaming out of the warp, as deadly as Dorn’s own spear. Warp energy boiled from its Geller field, fading to nothing in the face of inimical reality. The wound it tore in space and time was healing by the time the Majesty and the Night’s Vigil caught up with their flagship, engines howling under the strain of keeping pace. Slightly ahead of them went seven swift escorts. As soon as they had achieved translation to real space their engine stacks flared, propelling them into a picket line ahead of the flagship. Yet even these swift darts were not a match for the speed of the Eternal Crusader.
 	Finally, unhurriedly, the dark grey arrow of the strike cruiser Revenant broke the membrane of realities. Its machine-spirit showed none of the eagerness of the other ten ships, and it hung back from the rest.
 	The Majesty was a heavy cruiser, Night’s Vigil a battle-barge. Both gargantuan craft in their own right, they seemed paltry things next to the Eternal Crusader. A reminder of mightier days, the flagship of the Black Templars boasted the capacity to carry more Space Marines than existed in the entire Chapter. That it was so was the Chapter’s honour and their shame.
 	The Black Templars vessels were black as night, save where white panels broke up their livery, as stark as mountain snowfields. The forward prow shields of the two battle-barges and elements of their superstructures were so painted. On the Majesty, round bull’s-eyes marked either side of the broad keel vane. Likewise, the escorts were decorated with white prows or command towers. Upon these fields the gothic crosses of the order were displayed, the mark of the first Templar, Sigismund, and all of his successors. 
 	The Revenant bore grimmer heraldry: crossed scythes and a baleful skull, that of the Death Spectres Chapter of the Adeptus Astartes.
 	The three larger ships fanned outward, escorts hurrying ahead, adopting combat formation as soon as they were clear of the system’s Mandeville point. The Majesty and Night’s Vigil burned their engines hard, barely matching the Eternal Crusader’s speed. Revenant tarried, coasting forward at half power, allowing a gap of one hundred thousand kilometres to open up between it and the Black Templars fleet before its engines ignited and it accelerated to match the others. 
 	Onward they sailed, towards cold, gaseous worlds orbiting a poisonous sun. Beyond it was the long dark of intergalactic space, a wall of night in which isolated galaxies shone, so distant they were no brighter than stars.
 	The Emperor’s Crusade had reached the last strand on the shores of the great void, the supposed capital system of the cythor fiends. The last of the Ghoul Stars.
 	The command deck of the Eternal Crusader was as quiet as the bridge of a warship could be. Servitors mumbled repeated instructions to themselves, and ratings and serfs talked in hushed, respectful tones, mindful of their masters’ silence. The Chamber Militant of the Ghoul Stars Crusade Inner Circle stood upon a command dais, offered out over the tiered ranks of deck crew upon a jointed steel arm. With them was Naroosh, fourth captain of the Death Spectres Space Marines Chapter.
 	They wore their full wargear. The Adeptus Astartes had their powered battleplate, while the unenhanced Serjeant Majoris Valdric, master of the Chapter’s warrior-serfs, and Shipmaster Baloster wore ornate suits of carapace. All carried swords and pistols. Arming servitors waited silently at the edges of the dais with boltguns and other tools of death. A number of serf crew waited attentively by consoles in the dais railing. A ring of servo-skulls hovered overhead.
 	The Inner Circle had their eyes fixed upon the holo-display, a glowing blue ball floating over the operations pit. Three hundred thousand kilometres ahead it showed two dozen cythor fiend ships of various classes, several of which the fleet had been chasing this past month. They had no formation, no common orientation. Their hulls, so recently sleek, bore signs of decrepitude. They floated in the void, decaying vessels in decaying orbits.
 	A voice sounded from a servo-skull, conveying the report of a bridge serf in the pit below. ‘Still no sign of anything, Lord Helbrecht. Enemy craft remain without power.’
 	‘This is the ship we fought above the World Crypt.’ 
 	Sword Brother Gulvein pointed with an armoured hand. A serf anticipated his needs and amplified the view in the holo-display. ‘Only three weeks ago it ran before us. It looks as if it has been abandoned a thousand years or more.’
 	A different serf spoke, his voice made mechanical by the intermediary of the skull-vox. ‘All auspex readings are negative, my lords. No life signs or energy. Their reactors are dead.’
 	Helbrecht rumbled deep in his chest.
 	‘A trap?’ suggested Valdric.
 	‘Let me take a strike team aboard one,’ said Bayard, Emperor’s Champion of the Ghoul Stars Crusade. ‘I will learn the truth of it quickly enough.’
 	Helbrecht shook his head. Bayard shifted, his frustration plain for all to see. His armour whined quietly.
 	The High Marshal lifted his mechanical arm. His forefinger hissed as it uncurled. 
 	Baloster moved to an instrument panel mounted upon the dais rail. 
 	‘Pick your target, my liege,’ he said.
 	‘That one. Vessel fourteen,’ Helbrecht said. 
 	Numerals assigned by Baloster blinked around Helbrecht’s chosen ship. ‘Master of Ordnance, have lance battery three target it amidships,’ ordered Baloster.
 	‘As you command.’ 
 	The serf’s voice sounded from the skulls. His shouts could be heard far below as he relayed the shipmaster’s order. Baloster adjusted the holo-field, bringing the chosen target into sharp focus. A strange-looking ship with an undulating hull, it tapered at one end, was bulbous amidships and flattened at the prow. Its fabric was greyish, with a rough texture, the whole being reminiscent of an insect’s paper nest. This fragility was illusory; such vessels had proven difficult to subdue throughout the crusade. 
 	A half second passed. A gentle tremor, undetectable to all but the superhuman senses of the Adeptus Astartes, joined itself briefly to the perpetual rumbling of the engines. A bright light from the holo-display bathed their faces. A column of energy stabbed out soundlessly from the weapon’s batteries upon the ship’s spine, slightly off centre of the vessel’s heading. The beam struck the middle of the xenos craft and the hull glowed hot. A series of explosions burst along its portside and gases vented from its interior. 
 	‘Enough,’ said Helbrecht. The lance cut out. 
 	The ships’ relative movements, slight though they were, had dragged the lance across the surface, leaving an ugly wound. Impelled by the impact, the ship drifted away.
 	‘Response?’ asked Helbrecht.
 	The edges of the breach on the ship glowed a moment. Debris cluttered threat cogitators with munitions false positives. They were discounted quickly, red icons blinking out on the holo-display.
 	‘No response from the xenos ships, my lord,’ said an augur officer through the skulls. ‘No weapons fire. No defensive measures. No sign of course correction. The ship is drifting without power.’ 
 	‘Again,’ said Helbrecht. ‘Lance batteries one through four. On my mark. Cut it in half.’
 	‘Lance batteries prepared, Lord Helbrecht,’ said the Master of Ordnance.
 	‘Fire.’
 	A quiet screech trembled in the air at the discharge of four heavy lances. Their energy beams converged on the centre of the craft, slicing it into two pieces that fell away from one another, the stern out towards deep space, the prow towards another ship.
 	‘Xenos craft destroyed.’
 	‘Time to impact of that fragment?’ asked Helbrecht.
 	‘Forty-nine minutes.’ 
 	‘The other vessel is taking no evasive action, my lord,’ said Baloster.
 	‘I say again that we board them!’ said Bayard. ‘There is some trick here. Let us undo it with our blades.’
 	‘The planet awaits. There is no resistance as yet,’ said Master of Sanctity Theoderic. ‘I suspect this to be a delaying tactic.’ 
 	‘Have they fled?’ asked Castellan Ceonulf. 
 	Baloster consulted his augur teams via vox. ‘There are no signs of other vessels in the system, my lords.’
 	‘That means nothing,’ said Theoderic dismissively. ‘There could be another fleet hiding behind the star, or employing shrouding technologies to cover their retreat.’
 	‘They have not done so before, my lord,’ said Valdric. ‘They have always waited for our attack.’
 	‘These are xenos. They are not above hiding dishonourably if it suits them. This is their last redoubt,’ said Theoderic. ‘My Lord Helbrecht, if this is not an ambush, the situation suggests to me an evacuation.’
 	Helbrecht’s lips thinned as he turned over Theoderic’s words in his mind.
 	‘Then do we hurry forward,’ asked Gulvein, ‘in an attempt to catch them before they flee?’
 	‘Can we afford to leave this armada behind us?’ asked Ceonulf. ‘We will expose our rear to a counterattack. All this might be a bluff.’
 	‘We could despatch augur probes – it would be quicker and a lesser risk than boarding,’ said Jurisian, Master of the Forge. ‘If they prove to be crewless and truly inert, then we will be free of the task of destroying them until we have dealt with the primary nest.’
 	The Inner Circle of the Ghoul Stars Crusade looked to their leader.
 	‘We have wasted enough time,’ said Helbrecht. ‘Obliterate them.’
 	‘Aye, my liege,’ said Baloster. He passed the order on, then bowed to his masters and departed the dais, following the stair down the support arm. Thence he went to the main floor, so he might better deliver the judgment of his lord. Dozens of deck officers and servitors set to work, all talking at once, calculating firing solutions and organising target priorities.
 	‘We should despatch deep probes in any case,’ said Jurisian, ‘and cast out a net of augurs. There is no sense flying into the system blind. This is a strange foe. I shall have the forge prepare autonomous servitor units. Whether they flee or lie in wait, we shall find them. Should I request the astropathic temple perform a scrying?’
 	‘Do it,’ said Helbrecht. ‘As you say, we shall find them and we shall destroy them.’
 	‘Praise be,’ said the others. 
 	Jurisian took his leave to arrange both matters. One by one, the members of the inner circle set out to prepare their commands for the coming battle, if there was to be one. Helbrecht was silent. He remained alone but for Champion Bayard, who fretted for the fight silently alongside his master, and Captain Naroosh, who stayed to the shadows by the dais’ edge. 
 	‘Destroy the ships, find their nest – it is too late, your efforts are aimless,’ said Naroosh, the grim envoy of the Death Spectres.
 	Helbrecht remained with his back to Naroosh. Bayard shot the Death Spectre a murderous look, but Naroosh was uncowed.
 	‘Best spend your wrath elsewhere, High Marshal, and leave the thankless task of containment to my brothers. The cythor fiends cannot be vanquished.’
 	Helbrecht ignored him.
 	‘Very well,’ said Naroosh. His voice was leaden, weary. ‘We are observers here, nothing more. With your permission I will return to my ship and await the outcome of your folly.’
 	‘You have my permission, captain,’ said Helbrecht coldly.
 	Naroosh bowed and departed. Helbrecht’s eyes never moved from the fire blooming among the dead ships, not until the fleet had been rendered to splinters of semi-organic debris and clouds of glowing gas.
 	Still no reprisal came.
 	Probes shot out from small exit ports set over the Eternal Crusader’s prow augur arrays. Square as coffins, they housed the disembodied, lobotomised brains of heretics repurposed by the Chapter forge as mono-tasked servitor units. With a steady rhythm they launched, until five hundred coasted in long strings on either side of the fleet. At a single command, their plasma torches ignited, accelerating them away on pillars of glowing gas. At a safe distance, they arranged themselves into formation, a network whose nexuses were spaced a million kilometres apart.
 	Acting as one giant antenna, they filtered the aether for signals. Faint messages sent by cultures forty thousand years dead were isolated and discarded. Alien chatter was hunted down, analysed and dumped. But space in the Ghoul Stars was unusually quiet, as if the entire sector held its breath in fear, and they found their target within hours, buried amid the thumping voices of pulsars.
 	The minds of the dead conveyed their findings back to the Eternal Crusader, ten light minutes behind them. They accelerated onward, until their scant fuel reserves ran out, the damned souls within having unknowingly earned their redemption.
 	The Inner Circle gathered in one of the Eternal Crusader’s many strategiums to hear the message. Jurisian activated the recording by mind-impulse via the nerve shunts of his armour.
 	An audio fragment played, high register shrieks that made unaltered men wince. The same sequence repeated three times.
 	‘Is that it?’ asked Bayard.
 	‘This is in no recognisable tongue or code,’ said Jurisian. ‘But it was sent only a few days ago, and is artificial.’
 	‘What does it say?’ asked Ceonulf.
 	‘There are complex algorithms here. I cannot tell,’ said Jurisian.
 	‘Have the monks look at it,’ said Bayard hotly.
 	Jurisian’s servo arms, folded neatly across his back, twitched in annoyance.
 	‘You are the Chosen of the Emperor, Bayard, and by his will you are included in the Chamber Militant of the Inner Circle. But watch your tone,’ warned Helbrecht. ‘Jurisian is wise and well-versed in secrets you can never grasp. Save your choler for battle.’ 
 	‘My lord,’ said Bayard. He dropped his head. 
 	‘You have, of course, consulted with Abbot Giscard,’ added Helbrecht.
 	‘Of course. The finest minds of the Monasterium Certituda have listened to it time and again. They also could discern no meaning. It is a multi-dimensional model. Of what, I could not say. This is not the science of the holy Emperor-Omnissiah – it is unclean, xenos filth. But I can tell you from where it came – the third planet of this system.’
 	The world in question hove into view on their chartdesk, blue and ominous. Screeds of information detailing its hostile environment ran almost to the floor.
 	‘The outer gas giant,’ said Ceonulf. ‘It is unlike any world we have found the ghouls upon.’
 	‘Nevertheless, it emanated from there,’ said Jurisian. ‘It was a wide broadcast, radio frequencies. Very primitive. I cannot say for whom it was intended, but it suggests the nest is located there.’
 	‘Very well,’ said Helbrecht. He drew his sword, that most holy relic of the Imperium, and held it aloft. His fellows bowed their heads. ‘By the Sword of the High Marshals, Sigismund’s sword, into which was forged a fragment of Dorn’s own blade, I take the following oath – that we shall purge this world of our foe, and cast the cythor fiends out forever from the Ghoul Stars.’
 	‘Praise be!’ intoned the others.
 	‘Let this world be designated 9836-18, the eighteenth planet targeted by the 9,836th Black Templars Crusade,’ said Castellan Ceonulf. ‘Let us hereafter refer to and name it as Grave Core.’
 	The fleet approached Grave Core unopposed. Large structures were detected in the upper reaches of its deep atmosphere. No signs of life were detected, but little could be told, for the cythor’s structures and the world’s atmosphere defied the fleet’s auguries. Cautiously, Helbrecht ordered his Chapter to investigate.
 	The pilot spoke. ‘Wind velocity is four hundred and thirty-six kilometres per hour and rising.’
 	The Thunderhawk’s bumping turned into a ceaseless shaking as the craft sank deeper into the thick atmosphere. Hydrocarbon snow blatted against the cockpit canopy, leaving greasy smears.
 	‘Be advised, brothers,’ shouted the co-pilot over the screaming of the engines, ‘we will drop through several layers of differentiated laminar flows. The disparity between currents is high. This will be a rough transit.’
 	The Thunderhawk bounced hard. Engines howled as they clawed for the air streaming ahead of the ship. It tilted forward, the rear bulled up by the rushing wind. The metal creaked as the pilot pulled the prow level, wind and engines raging at each other impotently.
 	‘Wind velocity seven hundred and two kilometres per hour and rising,’ said the pilot. ‘Hull temperature twenty thousand degrees and rising. Air temperature two hundred degrees Kelvin. It is cold, brothers.’
 	The Space Marines, locked in their cradles, said nothing. The Black Templars were as belligerent as they were religious. If many of them spent their time from launch to insertion in prayer, equally there were those that liked to boast and joust with words before battle was joined. But this was a grim undertaking, an especially vile foe. The turbulence shook their tongues in their mouths, making them grit their teeth. Instead they silently focused upon the divine majesty of the Emperor and the righteousness of their cause.
 	The juddering image of an alien platform was projected into their helms. The habitat leapt from the display as if it was trying to escape, the result of the augurs mounted on the gunships repeatedly losing their lock. Although the Thunderhawks were being shaken to the edge of destruction by the planet’s violent atmosphere, the platform did not move so much as a millimetre.
 	The habitat swelled in the forward view. Similarly fluted as the cythor fiends’ spacecraft and made of the same papery organics, the bulk of it was a thicket of branching tubes, intersecting each other to form a three-dimensional mesh two hundred cubic kilometres in extent. Large hive-like structures were embedded in this network. Straggling tendrils twisted upon themselves outside this mass, as if they had attached to something now removed. Flat platforms that resembled great leaves were situated at various points, all at different inclinations to each other. The structure was grey and scabrous. Growing upon it were citadels of crystal, their clean, sharp planes a contrast to the fungal roughness of the rest. These were hard to see, hidden in the folds and frills of the habitat. Upon other worlds Helbrecht’s men had seen such glassy forts, although built upon solid ground. These had glowed with witchlight that danced in the stone’s depths. Not here. These were dead, mineral tumours on the habitat. 
 	The flight of gunships split, fighting to keep themselves from smashing into the habitat or each other. They headed for different areas of the alien tangle, seeking level ground to alight upon. Searchlights snapped on, dazzlingly bright on drifts of blue snow. 
 	No fire came to greet them, no message. No shields were raised or warnings uttered. The Black Templars landed unmolested. One by one their engines cut out, leaving the howling of the wind unopposed.
 	Helbrecht chose a wide space, a near-flat leaf that intruded some way into the root tangle between two of the papery hives. The pilot put the ship down as close by one of these structures as he could, seeking to shelter his brothers from the deadly winds. The ramp slammed down. An inrush of atmosphere equalised interior and exterior pressures with a bang. Helmet signums chimed warnings to their wearers as the oxygen-nitrogen mix filling the cabin was roughly compressed and chased out by Grave Core’s frigid, hydrogen-heavy air.
 	‘Onward!’ snapped Helbrecht. Fearing his prize to have slipped his grasp, his humour was poor. He shrugged off his flight cage before it had finished retracting and stalked outside, Sigismund’s sword already in his hand. The fifteen power-armoured Space Marines of Helbrecht’s command squad and Crusader Squad Victorious hurried out. Five Terminator-armoured Sword Brothers disembarked behind them, Sword Brother Gulvein at their head.
 	Wind snatched at them, buffeting even these potent sons of Terra. Caution overtook their battle lust. The surface was slippery with oily organics and frozen gas. Armour maglocks were activated but found nothing to grip; the ground was entirely non-ferrous. A barrage of sleety methane cut straight lines across the platform. Visibility was low, the wind deafening. Lightning crackled in the distance, spreading zig-zag networks through exotic gases. Plasma sprites ignited there, skittering like live things through the upper atmosphere. Helmet systems buzzed and fizzed with each electric blast.
 	‘My lord!’ shouted Gulvein. ‘An entry!’ He pointed with his power sword. The length of it sparked as snow was annihilated upon its energy field.
 	Helbrecht marched toward the entrance indicated – a vertical slit, far taller than it needed to be to accommodate the cythor fiends. A bipartite door, seamed raggedly down the centre, barred the way within. Helbrecht pushed at it, but it would not yield. His suit systems showed him a thick wall either side.
 	‘Breaching charges!’ he ordered, his words almost lost to the roar of the weather.
 	Two Space Marines of Squad Victorious ran to do his bidding, securing bulky meltabombs to the door. They activated the mechanisms and retreated. A bright fusion reaction consumed the bombs, most of the door and part of the wall. The xenos material fell away to soot that spiralled off on the wind. Helbrecht kicked his way inside.
 	Gulvein shouldered his way through, bringing down more of the weakened material and widening the breach. He came to stand by the High Marshal. Helbrecht was at the very edge of a precipitous drop, his cloak whipping around his legs. A massive space was before them, somewhat like the interior of a beehive hollowed of its combs. The edges were crowded with twisting walkways that led to randomly placed pods around the periphery. The centre narrowed as it dropped, until it was a few metres across. There a small hole glowed with blue world-light, affording a view directly down to the planet’s core. A crystalline structure hung from the apex of the building’s ceiling many hundreds of metres overhead. Suggestions of ramparts could be teased from its confounding layout, but again the crystal was lifeless and smoky, lacking the flowing light-forms seen on other ghoul-worlds. 
 	Hydrogen winds whistled through the Space Marines’ entry point, hooting along the unrailed walkways in a near melody disturbingly close to the sound of a human voice.
 	The Space Marines of Helbrecht’s group entered the chamber and fanned out. Squad Victorious took the upper levels. Helbrecht’s command group fell in around their lord. Gulvein’s Terminators stopped a short way from them.
 	‘Castellan Ceonulf.’ Helbrecht signalled his second in command. His voice seemed unnaturally loud after the tempest outside. Static hiss filled all their vox beads, as if the world growled in its sleep.
 	‘Lord Helbrecht.’ The voice that replied was not the castellan’s.
 	‘Forgemaster Jurisian? Where are you?’
 	‘About three thousand metres from your position.’
 	‘Are you in contact with the others?’
 	‘I have found Bayard’s group. He moves to join my Techmarines. Effective vox is down to pitiful distances. I can attempt a signal boost within a few moments.’
 	‘Do you have any notice of the foe?’
 	‘None, my lord.’
 	‘Then we shall make our way to your position and join with you and Bayard,’ said Helbrecht. He brought up a thumbnail map in his visor and planted a rendezvous marker upon the schema with his mind. The map skipped and juddered with interference, much of it coloured in hazy reds and uncertain purples. He had a firm lock on Jurisian, but the other Black Templars’ locators skittered from place to place as his armour’s spirits struggled to correctly place them. 
 	‘Brothers, follow,’ he ordered.
 	They walked around the chamber upon walkways that widened and narrowed without reason. Squad Victorious covered their lord and his veterans, boltguns sweeping across the great beehive of the room. No threat presented itself, and the Black Templars’ frustration grew.
 	On the far side there was another door. Helbrecht stopped, his command squad and Gulvein’s Terminators halting behind him. The door was as the other had been, an uneven shape sealed up the middle, rough and tight. But he found himself unable to judge its actual size, and when he examined it closely its lines shrank and warped without seeming to move. His sensorium pinged uncertainly. The heat outline of the door writhed with menace.
 	‘This door. My sensorium cannot get a firm hold upon it.’
 	‘It is odd in appearance, my lord,’ said Gulvein.
 	‘You see nothing amiss beyond that, Sword Brother?’
 	‘No, my lord.’
 	‘It shifts, as if presenting new aspects of itself to me.’
 	‘I see it entire and unmoving, my liege,’ said Gulvein.
 	Helbrecht looked again. This time, he saw nothing untoward. Frowning, he ran his sensorium feed back. Sure enough, there was the evidence: the door’s lines convulsed in the recording. ‘The mind might play tricks, Gulvein, but the spirits of machines cannot lie. What I saw was real. Sword Brethren, excise this door from its setting. Widen it. If there are defensive mechanisms within the wall, they will not catch us unawares.’
 	‘As you command, liege,’ said Gulvein.
 	Three Sword Brothers stepped forward. The stark blue light of active disruption fields reflected from the angles of the Black Templars’ battleplate as they smashed the wall to pieces. They battered with thunder hammer and chainfist until the door was obliterated, and half a metre’s thickness of broken, dry material lay exposed to the air. They ceased as one, judging the job finished. A blizzard of fine fibres wafted on currents of hydrogen-rich air.
 	‘It is done, my liege,’ said Gulvein.
 	The Terminators’ suit lights played about the interior of the room beyond. A floor sloped gently to some point in the middle, past the reach of the Terminators’ lamps. Tessellated, pentagonal blisters covered the wall as far as they could see. Acoustic pings emitted from the Space Marines’ armour painted a sound-image of a huge space.
 	‘This room is too large,’ breathed Brother Guthrith of Helbrecht’s command squad.
 	‘It does not match the outer shell of the habitat, my lord,’ said Gulvein.
 	Helbrecht had already seen this himself. He overlaid the supposed dimensions of the exterior upon what he saw of the interior. There was no fit between the external contours and the internal. His tactical map jumped and shifted.
 	‘This place is unwholesome,’ said Helbrecht. ‘Be wary. Be vigilant. I detect the corruption of an alien witch.’
 	‘Then we shall burn it upon the fire of the Emperor’s abhorrence,’ said Gulvein.
 	‘Praise be,’ the Space Marines replied.
 	Into the room they went, ever at the ready. Gulvein’s Terminators strode ahead, suit lights blazing, their lanterns of faith flickering at their sides. After three minutes, the cones of light emanating from their shoulders struck the far wall.
 	‘This is beyond reason,’ said Gulvein wonderingly. ‘What manner of evil is at work here?’
 	Helbrecht walked toward the room’s middle. The floor was rough underfoot, and rasped against the metal of his boots. They saw now that the chamber was a dome, five hundred metres across, the floor concave. The air was entirely still, the roar of the atmosphere outside absent.
 	‘My liege.’ Brother Eadwine of Squad Victorious voxed his master. ‘I have found trace of the foe. Dead. Here in one of the cells.’
 	The reaction to Eadwine’s announcement was instantaneous. All three squads went into a higher state of readiness. On their visor displays, threat indicators tracked upwards.
 	‘Check more of them,’ Helbrecht ordered. He strode toward the waiting Space Marine. Brother Eadwine stepped back from the cell. The fold of material he had been holding open with his bolter sprang back. Helbrecht grabbed it and wrenched it free. It collapsed into fragments as he did so. The lord of the Black Templars looked into the space behind.
 	Crammed inside, its spindly limbs wrapped tightly around its slender body, was a cythor fiend. There was the long head with a tiny mouth and no noticeable sensory organs, and a pair of long arms and legs, each with two more joints than human limbs. There were no identifiable muscle fibres in its flesh, which cloaked crystalline bones and was watered by a weak, benzene-based blood. But whereas the hides of those they had slaughtered elsewhere had been smooth and silvery, this one’s skin was as grey and rough as the fabric of the habitat. A fine web of gossamer strands covered it all over, somewhat akin to the silk spun by worms, but sparser and thicker. Helbrecht reached out a burnished bronze hand. When he touched the flesh it flaked away, as friable as burned paper.
 	‘In here too, my lord,’ called another.
 	‘And here.’
 	The Space Marines tore open more and more of the warty blisters. In most were desiccated corpses of cythor fiends, the life long fled from them.
 	‘What does this mean?’ said Gulvein. ‘Have they slain themselves in the face of our arrival?’
 	Before Helbrecht could answer, a garbled message burst across their closed vox-net, cut off as soon as it began. Banging followed, faint but unmistakeable.
 	‘Boltgun fire,’ said Helbrecht. ‘Ceonulf has found the foe. Praise be!’
 	‘I cannot raise him, brother,’ said Gulvein.
 	‘Nor I,’ said another.
 	‘Then we must find him,’ said Helbrecht. ‘Now.’
 	Through winding ways that doubled back upon themselves, Helbrecht and his men hurried, the sound of battle growing tantalising near then far again. Eventually, Helbrecht’s sensorium locked onto the locators of the other group, and they made all haste to the aid of their brothers. They crashed directly through a thin wall, bursting into a narrow hall where Ceonulf and his strike group were sorely embattled.
 	Ceonulf’s men were grouped tightly upon a bulge in the floor, Ceonulf at their centre. Four of their brothers lay dead upon the deck, with two more badly wounded. Boltgun shots punched through the air in all directions, blasting puffs of spreading fibre from the habitat’s fabric.
 	‘Where is the foe?’ roared Helbrecht, casting about for their enemy.
 	‘High Marshal!’ shouted Ceonulf. ‘Take care, my lord!’
 	The Space Marines searched in vain for the cythor, but saw nothing. The fifteen remaining men of Ceonulf’s group continued firing wildly. A stray round ricocheted off Gulvein’s armour into a ridge upon the wall where it embedded and exploded.
 	‘Cease fire, castellan!’ barked Gulvein. ‘You fire at nothing.’
 	‘Wait! They return!’ replied Ceonulf.
 	Chimes rang in their helmets, warning of spikes of exotic radiation.
 	‘There!’ shouted Helbrecht, pointing to a space to the left of Ceonulf’s circle.
 	Things that defied categorisation shimmered into being, intersecting layers of impossible shadows that flowed into one another in a manner that hurt the human mind. They were undeniably sentient, and hostile. They writhed through the air, anticipating the track of bolt rounds and slipping around them. Ceonulf’s men let out battle cries and concentrated their efforts. Helbrecht’s group spread out, surrounding the shapes and lending their own might to the fight. The creatures were caught in a murderous crossfire, but unbelievably they passed through it unharmed. They closed upon Ceonulf’s group, then leapt amid the combatants. For the duration of an eyeblink, they took on recognisable form: humanoid creatures of pure shadow whose skins writhed with glowing marks. Curved blades descended, dragging trails of condensing hydrogen fog after them. Once, twice. The crack of ceramite being breached cut through the sound of guns. Two brothers fell, one dead, the other clutching at his neck.
 	The creatures slipped out of existence, all indication of their presence abruptly vanishing.
 	Helbrecht’s men ceased firing and lowered their weapons in confusion, Ceonulf’s men following suit a moment later.
 	‘We were attacked fifteen minutes ago, my lord,’ voxed Ceonulf. ‘They appear, attack, withdraw. Four times they have done this. We have three minutes, ten seconds until they attack again, if their previous pattern holds true.’
 	‘Have you slain any of their number?’
 	‘No, my lord,’ said Ceonulf angrily.
 	Helbrecht pushed his way past his men. ‘High energy indications when they appear suggests beings of nought but warpcraft. They can avoid our weapons.’ He looked to the floor. A single patch of glowing blood sparkled there, although it was hard to look at, appearing to be upon the floor one instant, then above it, then passing through. ‘This is devilry,’ he said. ‘But they can be hurt. They evidently have form. What has form can be trapped.’
 	‘Two minutes, my liege.’
 	‘Graviton guns! Meltas!’ Helbrecht ordered. ‘We will see how they fare when they can no longer move. Cage them in bolter fire, bring them down with the gravitons and destroy them.’
 	An impromptu fire-team of two graviton guns and a meltagun were deployed to Helbrecht’s instruction, opposite Ceonulf’s position.
 	A minute later the odd radiation returned, starting a wail of alarms in their helms. A second after that the creatures returned, hauling themselves from dark spaces near the ceiling. The patterns of their bodies glowed a throbbing blue, green, red and gold.
 	Once again, the Space Marines lay down a withering curtain of fire. Watching carefully, Helbrecht saw that some rounds did indeed hit the creatures, but they passed through them and did not detonate. The passage of the bolts hurt them, for he saw the squirming shadow of their beings convulse and flicker more quickly. He waited until they had been shepherded together.
 	‘Now, brothers, now!’
 	Pulses of force nudged Helbrecht as the gravitons fired. The effect was immediate. The creatures shrieked. The shades that made them were violently arrested, and they solidified into the forms seen before, though now they were wracked with agony. Mouths opened, wide and full of razor teeth. Long pale hair flicked across featureless faces. They jerked around, unable to free themselves. The roar of the meltagun announced the death of the first. Before the second met the same fate, Helbrecht strode over and plunged the Sword of the High Marshals into the creature. He gasped at the shock of the contact. A deep cold surged up the blade, penetrating right to the interface of his bionic arm with an intensity that burned.
 	Helbrecht held fast. The darkness of the creature’s body ran like oil, fleeing from the bite of the holy sword towards the shadows around Helbrecht’s feet. As if dragged at by some force exerted by the blade, this darkness was sucked back toward it, turning for an instant again into the form of a shadow-man. Helbrecht saw slender, pointed ears, a hooked blade and pupil-less eyes that blazed green. Then it collapsed into itself, arms, legs, head and all, compacting into a dense column of purest black that shuddered then stilled. All the light fled from it, the room dimmed, and the column ceased its movements. Helbrecht twisted his sword, and the corpse collapsed into a sift of ash.
 	Silence fell on the battlefield. The Black Templars waited tensely for a further three minutes ten seconds, but no more creatures came.
 	‘These are an unusual enemy,’ said Helbrecht.
 	‘Where are the cythor fiends?’ said Ceonulf.
 	‘We found many dead, in a chamber near our ingress point,’ said Gulvein. ‘Maybe these things killed them.’
 	‘The ones we saw showed no sign of injury, brother,’ said Helbrecht. ‘And this thing had the seeming of an eldar wretch.’ He gazed at his sword edge thoughtfully.
 	‘Then what are they doing here?’ said Ceonulf. ‘Are these then the cythor? They are of a different form, but I have heard of stranger filth. Perchance they attempt to deceive us.’
 	‘No,’ said Jurisian heavily. The Master of the Forge came unsteadily through a door opening onto the chamber. One arm of his servo-harness had been sheared off. A crack in his left thigh plate was bobbled by sealant foam stained with blood. Several brothers and Bayard followed him, his black sword smoking. The number of their party was much reduced. ‘They are not the cythor, my brothers. They are their hunters.’ He stood a little taller, one human hand and a limb from his servoharness pressing into the wall for support. ‘Come, I have something to show you.’
 	‘I came across this place not long after we spoke, my liege,’ said Jurisian.
 	He had led them down a short yet convoluted passage to another large chamber. Within were thousands of corpses floating in the air at different heights and at no common orientation. Some lay peacefully, as if in deep sleep. Many others were contorted, terror clear on their faces. The majority were human, but there were many aliens there also. The larger proportion of the humans were not readily identifiable as Imperial, but representatives of cultures known and unknown. The xenos likewise were of differing types. All were united in death, but most markedly in their appearance. Their bodies were hollow, their skins transparent; they appeared almost as glass sculptures. They would perhaps have been mistaken for such were it not for the clothes, trinkets and weapons they wore, and the augmetics that persisted still in some of the more advanced. 
 	The Black Templars – Helbrecht, Jurisian, Bayard, Gulvein and Ceonulf – gathered around one of the corpses. Whatever process the man they examined had undergone had affected only the organic matter of his body; the nerve splices of his augmetic eye were clearly visible in the bowl of his skull. This one differed in one other important aspect also. His remains were full of a marbled glow, blue and green, red and gold, the sole lit lantern in a room full of extinguished lights. Helbrecht pushed it gently. The corpse moved into a new position and remained there, unaffected by momentum.
 	‘He is the last,’ continued Jurisian. ‘All the others have finished the process. They have been consumed.’
 	‘There must be thousands of them,’ said Ceonulf.
 	‘Tens of thousands,’ said Jurisian. ‘And there are other chambers like this.’
 	‘Then where are they, and what is this thing of light here?’ said Bayard angrily. 
 	‘Give me your hypothesis, Forgemaster,’ said Helbrecht.
 	‘I do not believe the cythor are entirely of our realm of existence, my liege,’ said the Forgemaster.
 	‘This stinks of warpcraft,’ growled Gulvein.
 	‘This is not the work of the warp. The geometries of the warp defy explanation of any kind. If anything, these dimensions here exhibit a greater complexity. Many of us have noticed the inconstancy of the rooms here, the lack of match between exterior and interior.’
 	‘Aye,’ said Helbrecht. ‘I have seen it for myself.’
 	Jurisian nodded, the movement accompanied by the faint whirr of muscle bundles. ‘Though complex, the dimensions of this place are explicable. This whole habitat is an expression of higher dimensional physics.’
 	‘Explain,’ said Gulvein.
 	‘The universe we exhibit comprises four dimensions – height, width, depth and time. These creatures are, perhaps, natives of more.’
 	‘You speak of the warp,’ said Bayard.
 	‘I do not,’ said Jurisian. ‘The warp is separate, unto itself, another realm entirely. There are more dimensions than the four in our own field of existence. It is through these that entrance to the warp is effected, and how some of the greater mysteries of the Adeptus Mechanicus are realised, but these dimensions are not of the warp. They are as real and physical as the heft of your sword, or the roundness of your bolts.’
 	‘I do not understand,’ said Bayard.
 	‘Imagine, champion, that you lived in a world of three dimensions instead of our four,’ said Jurisian patiently. ‘Width, depth and time. You would have no concept at all of up or down, as there would be no height. It would appear perfectly normal to you. But that would not mean that height did not exist, only that you are incapable of perceiving it. So it is here.’
 	‘You speak in riddles. If such a place existed, I would be able to see it. I can see no flat world, and so it is not there!’ said Bayard.
 	‘I speak of the greatest mysteries of the temples of Mars. It is not given to you or even to me to understand them, but that does not mean they do not exist.’
 	Helbrecht spoke. ‘You posit then a creature that exists as a physical being, not a witch or daemon born out of the warp?’
 	‘Yes, my lord. These new forms of the cythor are as real as you or I, but possess further dimensionality to them that makes them difficult for us to perceive. Forgive me, my lord, but I am unable to elucidate further. This field of study is the preserve of the greatest of the magi of Mars. My only knowledge of it is practical – the application of these prayer-equations to the proper functioning of field generation and suchlike. I do not know sufficient incantations to reveal the secrets encoded within this man or this building.’
 	Helbrecht gestured at the glowing corpse. ‘And what is this then, Jurisian?’
 	‘These are remarkable creatures, my liege. A fine enemy, deadly and complex. This, I believe, is how they reproduce.’
 	‘You speak as if these xenos filth exceed mankind in perfection,’ said Bayard.
 	‘I do not, for that is not possible. Their very nature is a sign of their weakness. Why do they trouble this place at all? For amusement? A weakness. To feed? A weakness. To breed? A very great weakness indeed,’ said Jurisian.
 	‘This is reproduction?’ said Ceonulf, looking at the endless floating dead.
 	‘Upon the seventeen worlds we scoured, we found no breeding population, no sign of permanent occupancy. Their cities were diamonds dropped on sand,’ said Jurisian. ‘Think of those worlds, brother, untouched away from their settlements. Did it not strike you as odd? When man takes a world, it is remade to his satisfaction. Many creatures do this, but not the fiends. According to the lore of the Death Spectres, the fiends come and then they go.’
 	‘Preposterous,’ said Bayard.
 	‘Hear me, brothers,’ said Jurisian. ‘There are creatures of the water of many worlds who must spawn upon the land, and creatures of the land who must spawn in the water. Perhaps these beasts are of that sort – they invade our existence to birth their foul progeny periodically, then depart.’
 	‘And the creatures we fought across the Ghoul Stars?’ said Bayard. ‘Limbs, flesh and blood. Not this glow of light here.’
 	‘Temporary forms, perhaps. I do not know. I am no magos biologis, brothers.’
 	Helbrecht made an angry noise in his throat. ‘And when the breeding is done, the creatures of the ocean depart.’
 	‘Back to the water,’ said Jurisian. ‘Whatever that is for them.’
 	‘And the shadow beings, they are some further manifestation of this?’ said Bayard.
 	‘I do not think so,’ said Jurisian carefully. ‘In some of the other chambers there are smashed corpses, like these, but broken, the glass of them scattered upon the floor.’ 
 	‘A hatching?’ said Ceonulf.’
 	‘I though so too initially, but these here have been consumed utterly, and are whole but empty. The cythor’s other form is of light – the creatures we fought are shadow.’
 	‘Then what do you suggest?’ said Helbrecht.
 	‘Where there is a glut of prey, my liege, there are always predators. We came here to destroy the cythor fiends and we find them departing. These other creatures, the shadow-eldar, have come to feed upon our foe.’
 	‘Ridiculous,’ sneered Bayard.
 	‘It is of no concern whether Jurisian is right or if he is wrong,’ said Helbrecht sternly. ‘Both xenos can be killed whatever hell-form they clothe themselves in. We shall root out the canker from this world, and purify the sector fit for the sons of Terra.’
 	‘Praise be,’ murmured the Black Templars.
 	‘We should consider withdrawal,’ said Ceonulf. ‘Destroy the world from orbit. We can strike these installations from the sky with ease.’
 	‘Where are the cythor, brother?’ said Jurisian. ‘Not here. To be sure we would have to annihilate the world. Exterminatus will prove difficult to enact upon a planet of this kind.’
 	‘Do you think something as mundane as Exterminatus will destroy them, brother, these things that can fold themselves around space at will? We must meet them with blade and bolt, as our brotherhood has done since the time of Sigismund. It is the only way to be sure,’ said Bayard.
 	‘How long do we have until this facility fails?’ said Helbrecht. He spoke tersely, his temper rising.
 	‘I cannot say, brother,’ said Jurisian. ‘I have my brothers-in-the-forge Yoth, Skardus and Herl scouring the place for mechanisms, but if what I suspect is true, we would not likely recognise them should we see them. They may well be hidden from us. For what it is worth, there are hints of energy fields about the structure, and they appear stable in nature.’
 	‘Monitor them,’ said Helbrecht. ‘I will order all brothers to withdraw upon your command as soon as you see signs of failure. Is that clear, Forgemaster?’
 	‘Of course, High Marshal.’ 
 	Helbrecht clenched his fists. ‘We must hurry,’ he said. ‘We must strike before our foe has fled or is destroyed by these others. I will not allow our glory to be snatched from us by degenerates.’
 	‘Then we must find to where the cythor have gone,’ said Ceonulf. 
 	‘There is an umbilicus, a root that goes down from the very centre of this habitat complex,’ said Jurisian. ‘I have re-examined the augur soundings of the fleet, my lord. There is a hint of something else down there, a little above the metallic boundary. Perhaps another habitat.’
 	‘Then we go down,’ said Helbrecht.
 	‘My lord, the pressure of the planet’s air increases a thousandfold. It is too great,’ said Ceonulf. ‘And the heat...’ 
 	‘Terminator armour is proof against such pressures and such heat,’ said Helbrecht. ‘Send for mine.’
 	The castellan was not to be dissuaded. ‘My Lord Helbrecht, to go down there is tantamount to suicide. Let others go in your stead.’
 	‘Do not say to me that I am of greater worth than other servants of the Emperor!’ said Helbrecht in a sudden rage. ‘This is my inaugural crusade. I called it. It falls to me to finish it. If I am to expire, so be it. I do so gladly in the service of the Lord of Man.’
 	None dared gainsay him.
 	Deep within the clouds of Grave Core, a sister platform to that above rode out the ceaseless storms. A twisting stalk gathered itself from the top of the structure to wind its way up through the surging clouds, where it joined to the centre of the dense mesh of the upper complex. At that depth the pressure crushed the air to a hot, soupy liquid. The winds turned into raging currents. Downdraughts of cooler air and upwellings from further into the planet’s roiling interior bubbled upwards. Down there was a core of hot ice, an intolerable country where diamonds rained on continents of hypercompressed carbon bobbing on viscous seas.
 	There, on the very boundary of a place where the conditions were inimical to all life, the fiends had their last outpost in the galaxy of man.
 	The stalk was half a kilometre wide, made of huge cords thicker than an armoured battle-brother and stronger than plasteel. Even so, by rights it should have been shredded, and it was not. The cord and the pregnant structure that fruited from it were still, untroubled by the liquid winds that spent their fury upon them.
 	But the Black Templars held that this inhospitable world was yet the realm of man, no matter that the light of Astronomican was faint there. They would not be thwarted. 
 	Around the juncture of the root and the structure were human artefacts, the shattered remnants of cybernetic devices. Only a few fragments remained, splinters of polished skull and steel, driven into the fibres that covered the stalk by the currents that had swept the rest of their components away. One remained whole: an extensively modified probe, proofed by the arcane secrets of the Eternal Crusader’s forge against the hellish environment. It had crawled down the stalk to its doom, but it had survived, and would for a few moments more, and that was enough. Within its armoured housing blinked a teleport homer, singing to the ships high in the void.
 	The liquid wobbled in the lee of the stalk. Bright light shone there. A shock wave of thin liquid burst outward. The Terminators arrived in a bubble of their own super-pressurised atmosphere, prepared for their transit, but despite the best efforts of the Chapter’s Techmarines the air was not quite of equal density as that around it, and the returning surge of liquid hydrogen rocked them on their feet.
 	Helbrecht, Gulvein and four others materialised – Sword Brothers Aelfgar, Sotrnem, Giraldus and Leofric. They skidded sideways in the wind. Safety lines deployed automatically from their armour, anchoring them to the alien structure. Aelfgar reached for Sotrnem, steadying him before he could be blown away.
 	Helbrecht looked at his Sword Brothers, their outlines wavering in the boiling hydrogen fluid. His armour creaked under the immense pressure. Currents yanked at him, threatening to push him from the structure to his death even in his Terminator armour. His movements were slow, his strength waging its own war against an entire planet. Status screed redlined all over his visor display, numbers jittering only increments below the armour’s utmost tolerances. He dismissed them in irritation.
 	Surging electrical currents made a mockery of the vox. He pointed downward. Giraldus hefted his chainfist, knelt and began to cut. He opened a wide space in the roof. One by one, the Terminators stepped through and fell rapidly, four metres down, trusting the might of their armour to absorb the impact.
 	They moved off to make space for their fellows as they arrived, suit lights flicking on to reveal a corridor as perfectly twisted as a rifled barrel. Three of them made a cordon for their high marshal. Aelfgar came after, Leofric last.
 	Inside the structure, the pressure was just as great, the temperature higher. But the vicious winds were gone, and the electromagnetic interference was zero. The tempest raged only metres over their heads, making the silence within sinister. Helbrecht clearly heard the soft breathing of his brothers over the vox.
 	‘This whole structure acts as an energy cage,’ said Gulvein. ‘If it blocks out the signal of the recall beacon, our brothers will not be able to hear our calls for retrieval.’
 	The white helmets of the Terminators looked to the bronze one of their lord.
 	‘Down,’ said Helbrecht. ‘We go down to victory or to death. It matters not. This is the path the Emperor has decreed, and we follow it until we succeed or die.’
 	‘Praise be,’ the others replied.
 	They followed a long, spiral tunnel that looped around and around the structure. As far as they could tell, it was similar in form to the hive-like buildings embedded in the habitat lattice hundreds of kilometres higher up, but much larger in scale, and solitary.
 	Mission clocks clicked onwards in their helmets. At the appointed times, the Black Templars sang their prayers in honour of the Emperor. The rest of the time they said little. There was no variation to the tunnel: it went on and on. For what seemed like a day they walked, proceeding ever downwards and inwards.
 	After some time, the tunnel changed, becoming wider. Branches emerged all around it in spiral patterns, tiny at first, then larger and larger, until it became apparent to the Space Marines that they were miniature replicas of the tunnel in which they walked, converging on one point as rivers converge on terrestrial seas. The road they followed was the main path, or so it appeared, but they did not trust their autosenses, and half expected their way to empty itself into one wider, or stop altogether.
 	‘Halt!’ said Gulvein. By this point the corridor had become vast, thousands of subsidiary tunnels corkscrewing into the space all around. ‘Movement!’
 	He pivoted his suit, moving the bulky shoulder guard from the hips. His suit beam stabbed out. A second met it, dazzling them.
 	Gulvein shut off his beam. They hefted their weapons, readying them for attack.
 	Staring back at them, from the curve of a fractally radiating tunnel, was a group of Black Templars: five in black, white and red, and one in bronze.
 	They lowered their weapons; the other group did the same.
 	‘A reflection,’ said Helbrecht aloud. His double said the same, the twinned echoes tangling along the convoluted interstices of the tunnel.
 	‘They appear not to be solid,’ said Aelfgar, and his double also spoke. 
 	‘Ignore them. It is witchery,’ said Helbrecht. ‘The Emperor protects us.’
 	‘Praise be,’ all ten Space Marines said.
 	They marched on, their doubles heading in the opposite direction.
 	The tunnels flowed together in infinite multitude. The solid phantoms became a more frequent occurrence. They walked round and round in spirals, coming stolidly towards Helbrecht’s party, or going away, or heading down other branches. They saw tiny versions of themselves treading their own paths in the subsidiary tendrils of subsidiary tendrils. When they sang their songs of praise, the complex thundered to prayers reproduced a million times.
 	At first the doubles were exact, but after a time they began to notice differences in their doppelgangers. Subtle at first – unfamiliar badges, perhaps, or a different brother’s name upon one suit of plate or another. These oddities grew wilder and more extreme. They saw themselves all in white, they saw groups of twenty or more, they saw themselves dead. They saw themselves in the yellow of the Imperial Fists, black gauntlets upon their armour. They heard vox chatter in their own voices but in languages that made no sense to them. They put all notice of these phantoms from their minds, concentrating upon their progression through the thick hydrogen medium that filled the tunnels. At all times the chief truth of ztheir creed was on their lips and in their hearts: ‘The Emperor protects, glory to the Emperor.’
 	And then they rounded a corner, and they were alone. They were notified of strange energies by their sensoriums, and their threat indicators, red since their arrival upon the deeper platform, shifted to an even angrier hue.
 	‘We grow close. Prepare,’ said Helbrecht.
 	A chamber met them, wider than could be guessed or measured. The dimensions of it were all wrong, sliding from their minds as they attempted to perceive them. A radiance shone at the centre of it, a tall slash that stretched from floor to ceiling.
 	‘A gateway, a tear in the world,’ growled Gulvein. ‘This is black sorcery.’
 	A multitude of shining beings crowded this brilliance. Their colours were those of the creature within the glassed man, but freed from their shells they took on shapes that were impossible for the eye to process – objects like soapy cubes that span about incomprehensible axes, or shoals of ever-changing pyramids. They orbited the light in a tightening triple helix formation that sank into its heart where the creatures were absorbed.
 	One form, far greater than the rest, hung over the light, its body playing complex rhythms of colour and shade.
 	‘It acts as shepherd,’ said Sotrnem. ‘Sending them whither it will.’
 	‘We have time if we are swift,’ said Helbrecht. ‘They flee our wrath.’
 	‘For the Emperor,’ Gulvein whispered.
 	‘Praise be.’
 	They stepped into full view, weapons raised, their armoured limbs working hard against the liquid air. They were noticed, and the pulsing of the shepherd picked up tempo. The crowds of flickering shapes spasmed as one, the helix twisted the faster, and the transformed cythor fled quickly into the light, disappearing from view in a shower of breaking rainbows. The chamber emptied impossibly fast; what had been a throng that pressed every side of the room become a crowd, then a small group. The Space Marines staggered forward, guns, swords and hammers raised. They made slow progress, their limbs snagged by more than the treacly atmosphere.
 	There was darkness too in this luminous place – the blaze of the light at the heart of the room cast black shadows in the nooks of the rippled wall. From here, the predators came.
 	‘Brothers! ’Ware!’ said Sotrnem. ‘Eldar daemonspawn.’
 	Shadows gathered at the corners of the room, black ellipses that rivalled the brilliance of the gate at the centre of the room in their blackness. From them issued the grim shapes of eldar-daemons. The liquid around them shimmered, condensed by the immense chill emanating from each. This effect made their forms waver, but they held true within their curtains of chilled air, appearing as solid creatures of blackness patterned with light, wild shocks of white hair around their heads. They wore no protection, even in the hostile depths of the atmosphere, but instead had long skirts around their legs that looked to be of flayed skin. Going in pairs, they stalked forward, approaching the edges of the herds of transformed cythor with sharded nets in their hands. Neither the shepherd being nor its charges appeared to notice this threat in their midst. The daemonkin stole forward and cast their nets into the shoal of cythor, dragging several pulsing, ever-changing shapes down to the ground.
 	‘They have our prey!’ roared Helbrecht. ‘They steal our prize!’
 	At this outburst, shadowy heads turned quickly. Several of the outliers turned from their harvest and passed into places cast into black shadow by the brilliant light.
 	They emerged again a second later, leaping from the dark places close to hand and into the Black Templars Terminators. There were seven of them, lithe and deadly.
 	Sotrnem was knocked sideways as one of the daemonkin struck him. Another came at him, hooked blade pulsing with sickly light. Sotrnem took the blow upon his stormshield. A shock wave burst through the thick air at the activation of the energy field. The eldar-thing fell back. A mouth appeared in the lower half of its featureless face, hissing at the Sword Brother. He shrugged at the other, knocking it from its perch upon his pauldron. Both were quick, even in the dragging atmosphere, and dodged his hammer’s blows.
 	Aelfgar and Leofric closed about Helbrecht, weapons ready. Giraldus opened fire with his bolter, catching one of the creatures in the shoulder as it poured itself from a crack in the wall. It was spun around by the impact, clawed at itself, then evaporated into wisps of shadow.
 	A third and fourth attacked Gulvein. He was wise in the ways of war, and stayed his hand till the last, reversing his blade and burying it into the sternum of one of the creatures as it came at him. The point of his power sword emerged from the thing’s back and the thick air curdled with its black blood.
 	By the gate of light, the grisly catch continued. Dozens of the daemon-creatures trapped the ascending cythor in nets of shadow and crystal. Many more of them were attracted to the Black Templars, emerging from the dark places, showing needle teeth in mouths that vanished when closed. They came from the thinnest sliver of darkness, crawling down the walls, hands plunging from hollows in the floor to grab at the Black Templars’ feet and greaves. Soon a crowd of dozens had gathered about the sons of Dorn. As they circled the Space Marines, they kept low to the ground, their movements as exaggerated and sinuous of those of a dancer. Close up, the glowing markings of their bodies could be seen as deep scars, cut or branded into their midnight flesh. All shone with a different light, this one green, another sickly yellow, a few an icy blue. The air wavered about them, a zone of churning currents where the deep chill that emanated from the creatures fought the pressure-heat of the room. The daemonkin’s numbers increased until they brought the temperature of the chamber low enough for the temperature gauges in the Terminators’ visors to drop.
 	‘Come for us, foul warpspawn, and see what it avails you!’ roared Gulvein. ‘You have tasted our mettle – my blade yearns for more of your blood!’
 	‘They will not attack,’ said Helbrecht. ‘They are craven. We have put the fear of Dorn into their hearts! They seek only to keep us from our prize. Well, I say – this will not pass! We have taken an oath to rid the galaxy of the cythor fiends. I will not stand idly by while my prize is denied me!’
 	‘Praise be!’ roared the Black Templars. Their blood boiled with righteous anger, and they threw themselves into the mob of daemonkin.
 	The watery air boomed with the crackle and banging of disruption fields. Ten daemonkin or more there were for every Terminator, but although the creatures crawled all over the Sword Brothers, they could find no way into the armour, and the Black Templars set about the glorious work of death. Gulvein slaughtered many, his sword moving slowly through the cloying air, but always to the right place at the right time. Giraldus brought several down with his boltgun, while Leofric and Aelfgar used their mass and crackling stormshields to force a path toward the fleeing cythor fiends. Helbrecht followed them, the sword of Sigismund jabbing and slashing into the packed mass of the creatures, slaying many.
 	The daemonkin drew back. Fell light played over their markings and a blast of terrible cold emanated from their outstretched claws. 
 	The passage of the energy churned the air, ripping oath papers and tabards from their mounts upon the Black Templars’ armour. The dark eldar concentrated their fire on Aelfgar. The blast caught him square in the chest, blazing against his eagle and cross where a thick sludge of freezing hydrogen formed. With a sickening bang, Sword Brother Aelfgar’s armour collapsed inwards and he was pulped. On Gulvein’s squad display, the pressure signifier for Aelfgar’s armour shot into four figures and the temperature map of his suit became blotchy. He died instantly, his vital signs running flat.
 	‘What wickedness is this?’ cried Gulvein.
 	‘It is witchery, brothers!’ roared Helbrecht. ‘Prayer is the answer! Devotion! Raise your voices to the God Emperor and we shall surely overcome them! Praise b–’
 	Helbrecht was cut short. Gulvein turned ponderously around, hampered by his armour and the environment. A daemonkin leapt at him. He thrust it aside, intent on his lord.
 	He was just in time to see Helbrecht be pulled through a dark shadow in the floor. The High Marshal vanished.
 	‘Helbrecht! The High Marshal! The High Marshal is taken!’
 	With a great shout of anger, the Black Templars stepped up their attack.
 	Helbrecht fell through air no thicker than that of the Eternal Crusader. He landed hard on a pile of bones that shattered under his weight. Dragged down by his armour, he plunged deep into them, their broken ends closing over his head. The sword of Sigismund was jarred from his fingers, becoming lodged in the tangle of skeletons above him. His hand closed around the honour chain binding it to his wrist and he yanked hard, tugging the hilt through the calcareous mess overhead until he could grip the sacred weapon once more.
 	Bones exploded outward as Helbrecht kicked his way free.
 	He was in a cavern of black rock. There was no light except that cast by his suit lamp and devotional lantern. The environmental gauges of his sensorium flickered, confounded by the abrupt change. The room was at almost normal Terran atmospheric pressure, and a few degrees above the freezing point of water. Thermal imaging revealed walls of blocky, cruel-edged rock with a near-uniform temperature profile. He turned about, scanning the room with his eyes and sensorium. There appeared to be only one way in, and between himself and that exit were many piles of bones. They came from every creature imaginable, and all, without exception, were bereft of their skull.
 	Helbrecht shifted his grip on his sword and made for the tunnel mouth.
 	He did not have to walk far before he came across the heart of the place, a large and ominous hemispherical ossuary chamber. Except for a few black spaces, the rock was entirely covered with skulls, far more than there were skeletons outside. They were impaled on dark iron spikes, arranged according to species and size in bands and whorls that made subtle patterns. These became starker the longer he looked at them. A dais of black stone was set at the centre of the room, discarded skulls mounded up around it, the broken fragments of others carpeting the floor from wall to wall.
 	The empty sockets of the mounted skulls glared at a space someway off the floor. Perhaps as an effect of this, the entire space throbbed with sinister energies.
 	‘A dark fane. I have come to the domain of the unclean,’ said Helbrecht. There was no fear in him, no concern at his displacement in space, only an exultation of the spirit. Surely the Emperor had ordained that he come here. Soon an enemy of the Emperor of Man would lie dead by his hand. He gripped his devotional lantern and held it up. ‘Come out, witch – I have been sent here by the Lord of Man to see to your doom. I bring the light of his magnificence to reveal your wickedness.’ 
 	A low hiss answered from the darkness.
 	‘Revile the witch! Destroy the unclean!’ bellowed Helbrecht. ‘Suffer not the alien to live!’ He raised his storm bolter and took aim at the skulls upon the wall. He let fly three rounds, and shattered a dozen of his captor’s trophies. ‘Praise be! Praise be! Praise be!’
 	He ceased firing. His boltgun smoked righteously.
 	‘You make a space for yourself.’ A low and sibilant alien voice defiled the Emperor’s language. ‘That is good. You are worthy.’ His foe was right behind him.
 	Helbrecht turned just in time to block a vicious swipe. The sword of Sigismund caught a hooked alien blade that burned with the power of baleful technology. He flung it outward with a sweep of his sword, meaning to riposte on the return and end his foe, but the thing was too quick, dodging backwards and launching a flurry of counterblows at Helbrecht’s head.
 	The thing was of the same ilk as the cythor’s hunters – black skinned, pale haired, clad in skins torn from the backs of other beings. The cuts in its body glowed with a greenish ghostlight. But this one had four arms with skilful hands that switched the blade with flawless skill, making the direction of its strikes hard to judge. The sword blurred through the air, describing deadly, decapitating arcs, crackling as it went.
 	But Helbrecht was no ordinary man, and even among the Adeptus Astartes he was reckoned mighty, skilled at arms beyond the art of any. He matched the creature blow for blow.
 	This pleased the monster. 
 	‘Yes, yes,’ it said, its voice a dire hiss. ‘Worthy indeed.’
 	A blow quick as thought flicked out, scoring Helbrecht’s armour with a bang. The Sword of the High Marshals sliced back in return, cleaving the air where the creature had been. As it leaned from the blow, its ragged fringe fell aside, revealing empty eye sockets as black as those of the skulls arrayed around the chamber.
 	Helbrecht and the thing duelled, neither forcing an advantage. They pushed each other back and forth across the chamber, Helbrecht’s boots stamping the bone upon the floor to powder. The creature was quicker than he, but Helbrecht was stronger and far more heavily armoured. The creature’s only defence was its speed. Neither showed any sign of tiring. The daemonkin was possessed of unnatural vitality, while Helbrecht was bestowed with the gifts of the Emperor. He sang hymns of hate as they fought, yelling into the face of the creature’s silence.
 	And so the duel could have progressed, the two locked in mortal combat until one stumbled, perhaps days later. But it was not to be.
 	The chamber rumbled. A deep, dark section of the wall vanished, and Helbrecht found himself looking into the gatehouse of the cythor upon Grave Core, blazing with light. He saw his men, free now of foes. Gulvein looked at him, his head huge and distorted.
 	‘I see him here!’ Helbrecht heard him say, his voice unimaginably distant.
 	The creature made a desperate lunge, a movement too quick for an unenhanced man to see, but Helbrecht deflected it.
 	‘Hurry, Gulvein!’ Helbrecht recognised Sotrnem’s voice. ‘The light is going out!’
 	‘He sees us! Praise be, he sees us!’ said Gulvein. ‘He lives!’
 	From the shadows of the alien’s lair an outstretched hand emerged, dripping alien gore and steaming with boiling hydrogen vapour. Gulvein was peering through a crack in space at Helbrecht, distorted horribly. To Helbrecht, Gulvein’s hand was normally sized, but his head appeared monstrous, as if viewed through a flawed lens.
 	‘Hurry, my liege! We must depart! It is over.’
 	Helbrecht glanced back, parrying another blow. His return this time caught the creature. It drew shadows to itself and flowed sideways, too slow. The point of Helbrecht’s blade raked across its ribs, only lightly, but such was the sharpness of the edge and the potency of the energy field encasing it that the creature howled in pain and drew back.
 	‘I almost have it!’ he shouted.
 	‘Now, my lord, or we shall perish!’
 	Cursing, Helbrecht glared at the eldritch headsman. It laughed wickedly.
 	‘I will end this duel, daemonspawn,’ said Helbrecht. He reached for Gulvein’s hand.
 	‘And I will take your head,’ said the creature, its voice soft and chill as blown snow hissing over ice.
 	Helbrecht took Gulvein’s hand. Gulvein hauled upon him, and the dark realm fell away. Helbrecht’s arm emerged through the head of a fallen daemonkin, bursting it apart. Gulvein tugged hard, and Helbrecht was pulled completely from the shadow realm back into the gateroom of the cythor.
 	‘I saw you, I saw you in its dead eyes, a... a reflection,’ said Gulvein. ‘Fell witchery, but you are safe, my liege!’
 	Helbrecht was disoriented only a moment by the enormous change in his surroundings. The eldar shadow creatures were either dead or gone, their grisly harvest concluded. The bodies of those slain slowly dissipated into shadow, their white hair wafting on the currents in the liquid air.
 	‘The cythor, did you slay them?’
 	‘No, my liege,’ said Gulvein, and there was shame in his voice. ‘It was almost done. They have escaped.’
 	At the cythor gate, the last of the lesser beings fell into the light. It collapsed to a single point, blazing polyhedrons slotting into each other until it was gone. The shepherd creature descended, coming to rest fifty metres before them.
 	Things that could have been limbs moved. Light danced over it. It observed them as Helbrecht raged against it powerlessly.
 	Somehow, the thing spoke to them. Not with words, nor with the mental powers of a psyker, but in some other way that burst their heads with pain.
 	OURS, it said. THIS PLACE. GO. NO RETURN.
 	A shaft of light leapt from the cythor shepherd, playing over them. To what effect they would never know. 
 	The creature regarded them for a moment longer. NOTHING, it communicated. YOU.
 	The shapes of its form folded into one another, the colours turning to reds that dulled to a deep glow, and it vanished. The light blinked out with it. The shadows lost their starkness. All life went from the structure, the confusing dimensions of the place catastrophically reverting to accord with the natural laws of the Emperor’s domain.
 	The structure groaned. A rumbling spread throughout. With a lurch it fell, pulled in by the planet’s enormous gravity. A section of it broke away, showing the raging, endless storms of Grave Core outside.
 	Pressure and temperature gauges in the Space Marines’ Terminator armour screamed. Plasteel and ceramite buckled.
 	A ping sounded in their helms – a teleport lock, made possible by the destruction of the habitat. A fizzing sensation prickled their limbs, and they were gone from the world.
 	The teleport sequence cycled down. The instant the last translation icon blinked out, six teleport pods blew apart, burst by the sudden pressure change of their contents. Super-dense, hydrogen-rich liquid air catastrophically evaporated, blasting servitors waiting around the pods off their feet. Emergency klaxons blared as the teleport deck was flooded with explosive gas, great fans chopping noisily round to suck the atmosphere free and vent it safely into space before it could ignite
 	Throughout it all, the monks of the Monasterium Certituda did not cease their canticle for the safe return of the High Marshal.
 	As soon as the all clear sounded, Jurisian was out of his observation galley, limping across the deck to the shattered pods. Five of the six Black Templars were safe, protected by their armour, although they were tangled in the wreckage of their pods. The sixth, Aelfgar, was a crumpled mess of broken ceramite leaking gore. Small fires and explosions went off around the deck as Jurisian reached Helbrecht.
 	‘Emperor be praised!’ he said, his mechanical arms pulling his lord free. ‘We achieved a teleport lock just after the habitats fell from the sky. What happened, my liege? Are the cythor gone?’
 	‘Yes,’ said Helbrecht. He held out his arms for his weapons to be unplugged and their oath chains unlocked by neophytes who hurried to attend to the battered knights. He wrenched his helmet from his head and handed it one. Sweat poured down his face.
 	‘You were successful, then,’ said Jurisian.
 	‘No,’ snarled Helbrecht, raising his hand angrily and clenching his fist. Jurisian feared a blow might follow, but it did not. ‘We were not. My victory was stolen from me by others. Neophytes! Bring me my power armour and clad me in it. I must do penance in the Temple of Dorn.’ He spat upon the floor. ‘This uncanny crusade is over.’