As all four of those black eyes fixed upon him, Corswain felt something inside his head, like a warp translation but sharper, like a pinprick in the centre of his mind. He tried to block out the sensation of fingers pulling apart his thoughts and memories, examining them one by one, but could not stop the creature's mental assault.

Suddenly the seneschal's limbs went numb. He stood up, with no volition, but was otherwise immobile. Around him, the other Dark Angels were just recovering from the shockwave of the creature's last attack.

Corswain tried his best to resign himself to his death, but it was hard. He never had thought his life would end like this, as helpless as a newborn, facing an enemy that he could not even begin to comprehend. He wanted to spit a curse, or dedicate his last breaths to his primarch and Emperor, but he was denied even this honour. His body was not his to control.

The nephilla reached out a bony finger and beckoned him forwards.

Lashing out with an armoured boot, the Lion sent the hound-like beast tumbling down the corridor. Taking half a dozen strides, the primarch brought both of his swords down across its back as it tried to right itself, carving it into three pieces that spattered into gore across the decking.

He stopped for a moment to assess the situation. The flight of stairs down to the main core chamber was only fifty metres ahead, and the passageway was free of enemies. He could hear his company fighting behind him, the retort of bolters echoing up from the stairwell he had just left. Though he knew his little brothers were in a dire situation, he had to focus on his objective: regaining control of the core so that the warp engines and Geller field could be engaged.

The comm buzzed as he stepped forwards, and he heard Corswain's voice. The seneschal sounded strained, as if speaking through gritted teeth.

'My liege, the way is clear to the warp core. You must come at once. There is something else here, something we cannot destroy.' The comm-link hissed for a few seconds. 'It... It wants to speak with you.'

The Lion entered the warp core chamber at a full run, taking in the scene in a few moments. Several dozen Dark Angels were stood around the perimeter, their weapons directed at a monstrous bird-like nephilla but not firing. In front of the creature was Corswain, standing immobile just a few metres from it, arms hanging limply by his sides.

Cease your attack or this one will be destroyed.

The words came to the Lion's thoughts directly, bypassing his ears. Their tone was soft and melodic, in contrast to the haggard, harsh-looking creature that had undoubtedly sent them. The nephilla's intent was immediately clear and he skidded to a halt, coming to a stop with his swords held ready to defend himself. There was no reaction from his warriors, and he guessed that the words were directed to him alone. He did not know whether their passivity was voluntary or enforced, but it was clear they were in grave danger.

'It is not I that launched an attack,' said the Lion, taking a step closer to the apparition. 'Leave now.'

And make a waste of all the effort that it took to reach this place? I have been searching for you a long time, Lion of Caliban.

There was something familiar about the creature's voice, like a half-remembered dream. The Lion could not place from where, but it was not the first time he had heard this. His mind stirred with vague recollections, of pleading and entreaty.

Yes, that is true. I have come to you before.

'Get out of my thoughts.' The Lion stepped to his left and focused on blocking the creature from his mind, mentally bringing up a shield as though he were defending himself against a physical attack. It was a trick he had learnt as he had stalked nephilla on Caliban. One of the bird-beast's heads followed him with its inscrutable gaze, the other stayed fixed upon Corswain.

That might work in the real universe, but not here. You are in my realm now, or at least teetering upon the brink of it. You cannot ignore me this time.

'I do not treat with aliens,' said the Lion, taking a few more steps to his left, closing the gap between himself and the nephilla.

Alien? Alien? There was despair in the voice. I am more than some simple creature of your universe. I am the giver and the receiver, the crux of fate, the master of the parallels. The past and the future are laid before me. Do not mistake me for some petty foe to be vanquished by mere might of arms.

'You have nothing to offer that I will accept.' The Lion was directly behind the creature now, its snake head still regarding him with an unblinking stare while the vulture transfixed Corswain.

That is not true. However, you do not desire power, that much is plain. Your ambition is woefully stunted for one of your abilities. You are happy to let your brothers dwell in the light of your father's adoration. You even sacrifice your own to stay true to the memory of what once was.

The two necks were starting to cross each other as the Lion continued his circling. He resisted the lure of the accusation in the creature's words, which echoed with the taunt made by the Night Haunter.

Freedom, Lion of Caliban. I can give you freedom. You know that you do not really care for these lesser beings. They are a distraction to you. Their frailties, their petty squabbles, are unnecessary trifles to be avoided. Even this war that you fight, it is without consequence.

'Horus cannot be allowed victory.'

Horus's victory is not your concern. All things are fleeting, even the lives of great Warmasters. I have witnessed the rise and fall of every civilisation in the universe. None of them can endure, Chaos always consumes them in the end.

That word Chaos resonated through the Lion's thoughts. He had a fleeting glimpse of eternity, of the entropy of the universe, ever-changing, new lives born out of death, of stars decaying to create worlds and worlds dying to form new stars, all in constant flux.

'The Emperor has shown us a new way. The Imperial Truth will endure for eternity.'

Laughter resounded inside the primarch's skull.

Foolish! Your Emperor is nothing more than a fraudster with grand ambitions. His empire is no greater than any other edifice of Mankind, and it will tumble just as easily.

The words were spoken with scorn yet they lit a spark of hope in the Lion's breast the creature spoke of the Emperor in the present tense. It thought that the Master of Mankind still lived.

The nephilla could not follow the Lion's progress any further with its snake eyes, and for a moment it broke its gaze from Corswain, serpentine head swinging towards the seneschal while its vulture-like visage fixed on the primarch.

It was only a split second but it was all the Lion needed.

Before its gaze was on Corswain again, the Lion launched himself at the nephilla, sword outstretched. With astounding speed it reacted, twisting its whole body in his direction, staff coming up to spew forth a sheet of forking energy.

'Kill it, Cor!' snarled the Lion as wreaths of crackling energy enveloped him, sending pain coursing through every limb, surging into his chest and pounding in his head.

With a roar, the primarch broke free from the net of lightning that surrounded him, still lancing his sword towards the nephilla's body. A hail of fire hammered into the creature from the encircling Dark Angels as Corswain leapt away, the seneschal's bolt pistol spitting rounds.

Predictable fool.

The nephilla's staff swept out, turning aside the Lion's first blow. Twisting, wings furling, the creature side-stepped the Lion's charge, its serpent head lashing out towards his throat with bared fangs.

The Lion turned mid-stride, dropping Hope which had been deflected by the nephilla's parry. His gauntleted fingers curled around the slender serpentine neck as the primarch allowed himself to fall to the ground. His grasp unbreakable, the Lion dragged the nephilla down with him, its chest plunging onto the waiting point of Despair.

Harmed but not slain, the nephilla reared up, taking the sword from the primarch's grasp, wings spreading once more, now bat-like and shimmering gold. Its vulture's beak rammed into the side of the Lion's helm as it sought to pull its other head free from his grip. Wings beating fiercely, it tried to lift away, but the Lion's grasp held firm as he was pulled back to his feet.

'Did you see this coming?' snarled the Lion, hammering his fist into the pommel of the half-buried sword, driving the blade fully into the nephilla. The primarch felt a moment of contact, something deep within him connecting with the substance of the nephilla. His anger raged, finding conduit through his arm, into his fist, given vent along the blade of the buried sword like white fire pulsing from the Lion's heart.

The creature's piercing shrieks ripped through the Lion's mind. Its body burst into a globe of power, filling the chamber with expanding flame that sent the primarch reeling, droplets of the molten sword pattering against his armour.

Silence descended. The black of his armour was covered with a patina of roasted gore and his mind was still throbbing with the death-scream of the nephilla. The primarch picked himself up, retrieved Hope from where it lay on the deck and made his way over to the warp core control panel. Much of it was scorched and broken, and he started to pull away cracked panels to expose the circuitry beneath. He made a quick assessment of the damage and activated the comm.

'Captain Stenius, I will have the warp engines operational in seven minutes. Ready the Geller field and prepare for translation.'

VI.

Once the Invincible Reason had translated fully into the warp, protected from the maelstrom of energy by its Geller field, the Dark Angels took the offensive. As had been proposed by Lady Fiana, the nephilla were much weakened, unable to draw on the power of their realm, making them vulnerable to the weapons of the Dark Angels. With the newly-restored Librarians and the Lion leading the purge, every part of the battle-barge was scoured, the remnants of the attackers driven out of hiding to be gunned down. For two days the scourging continued, passageways and gun decks, engine rooms and mess halls, dormitories and drill ranges resounding to the roar of bolters and the vengeful battle cries of the First Legion.

Nearly three hundred Dark Angels had fallen during the fighting, many of them within the first hours of the assault. More than twice that number of Legion serfs and crew had also been slain. The apothecarion was filled with those legionaries who had survived, some of them with hideous, grotesque wounds that festered with unnatural decay or continued to blister and bleed despite the best efforts of the Apothecaries.

Amongst those being treated was Fiana, who had survived the backlash of her third eye, but only barely. She looked to be a wizened, aged crone as she lay in her bunk, her body otherwise undamaged but her mind dislocated by the psychic assault suffered at the whim of the nephilla. Despite this, she and her fellow Navigators did all they could to assist the legionaries. Cut off from the warp by the Geller field, the nephilla's presence was easily discernable by their othersight, and they guided the Dark Angels kill squads unerringly to their targets, no matter how dark and isolated their hiding places. On top of this, the Navigators had to guide the Invincible Reason to Perditus, pressed to find the utmost speed by the urging of the Dark Angels' primarch.

It was eight more days of travel before the Navigators announced that they were in the vicinity of Perditus. Lady Fiana had recovered a little more from her ordeal, and was able to take her place in the rota of Navigators steering the ship. On reaching their destination, she requested an audience with the Lion before she would allow the Invincible Reason to translate back to real space. As before, the Lion met with her in his throne chamber, attended to by Stenius and Corswain. Fiana had noticed the seneschal check on her condition several times when she had been in the apothecarion, but she had not had the opportunity to discuss what they had encountered. Now was not the time, the Lion was clearly impatient with the delay in translation.

'There is something amiss, lauded primarch,' Fiana explained when the primarch demanded to know the cause of her hesitation. She was forced to lean heavily on a cane that one of the Techmarines had constructed for her from a length of ribbed piping, its finial fashioned from a piece of jet-black stone, the ferrule made from a carefully cut section of the material used in the joints of power armour. Her voice had become a wheezing whisper, her words punctuated by heavy gasps. 'By all calculation and observation, we have reached Perditus, yet for the last three hours we have been unable to sight any warp beacon to confirm this categorically.'

'The storms?' suggested Corswain.

'On the contrary, the warp is incredibly placid in this locale, disturbingly so. There is almost no movement whatsoever, as if the currents have been flattened, stretched into non-existence. It is this dampening effect that I believe obstructs the beacon signals.'

'It is no mystery,' said the Lion, his expression easing into a less agitated state. 'We observed the same when we first came here. This pooling phenomenon is, I was led to believe by the Mechanicum, a side effect of the work they are performing at Perditus. It confirms that we have arrived. Make arrangements for translation as soon as possible, Captain Stenius.'

'There is something in the warp causing this oddity, lauded primarch,' insisted Fiana, taking a laboured step towards the primarch. 'I and the others can feel its presence, sense the pressure it is placing on the warp. The stability here is hiding a far more turbulent undercurrent.'

'Your observations have been noted, Lady Fiana,' said the primarch. He stood up, ending the conversation. 'Please continue to make your reports on the matter to Captain Stenius.'

Fiana railed against this casual dismissal, unable to shake the disquiet she had felt at this sinister discovery, but knew better than to debate the matter with the primarch. He was already turning his attention to Corswain. She dipped her head in acquiescence, understanding that the mystery would have to be solved another day.

Several Dark Angels ships had already made transition to the Perditus system when the Invincible Reason broke through into real space and established contact, though nearly a dozen vessels were still in transit in the warp. Fleet movements had never been easy through the warp, and the storms had exacerbated the problem considerably. It was one of the main reasons the Dark Angels had been unable to force a decisive encounter with the Night Lords in Thramas; by the time sufficient vessels arrived in a system to confront the enemy the elusive Night Lords had time to escape direct conflict.

The Lion weighed up his options: to wait for more of his flotilla to arrive or to press on towards the Mechanicum station on Perditus Ultima. Surmising that the Iron Hands and the Death Guard would both be aware of their arrival, the primarch saw no cause for delay and directed the five ships present in his fleet to advance in-system at full speed.

Passing the uninhabitable gas giants at the edge of the system, the Dark Angels picked up sensor readings of two fleets engaged in a protracted manoeuvre for position around Perditus Ultima, the closest planet to the star, on the very edge of the habitable zone. Ident-codes and intrafleet signals marked out the vessels as Iron Hands and Death Guard ships, each flotilla numbering no more than half a dozen ships; even combined they would be no match for the might of the Dark Angels that would be arriving. Despite hails, communications could not be established with either fleet, or the ground station on Ultima.

Crossing the orbit of Perditus Secundus, just five days from their destination, the warriors of the First Legion were in range to detect forces deployed onto the surface of Perditus Ultima. Comm-intercepts indicated that a stalemate persisted there as well as in space. The ships of both the Iron Hands and Death Guard were conducting an extra-orbital ballet, each trying to gain position over the world to support their troops on an offensive action, but neither was able to gain the upper hand without risking a decisive, and potentially devastating, space-borne engagement; thus the two sides were locked together at arm's length, neither prepared to wager possible defeat against a push for victory.

Summoning a council of his captains, the Lion determined a course of action for the Dark Angels.

'We will position our fleet directly between the Iron Hands and Death Guard, and announce that all hostilities are to cease,' he told the assembly of officers gathered in his throne room aboard the Invincible Reason. 'If neither side is willing to risk an engagement with each other, for certain they will not be keen to take on a fresh foe.'

'A risky proposition, my liege,' said Captain Masurbael, commanding the frigate Intervention. 'What is to be gained by placing ourselves in harm's way? Our arrival and numbers will be known to both sides already, there is no reason to expose ourselves to the danger of direct attack.'

'Purpose and threat,' replied the Lion, smiling coldly. 'We are to make our intent and determination crystal clear from the outset, lest our adversaries think we issue idle demands. Perditus is under the aegis of the Dark Angels and the sooner we establish the fact, the swifter we will conclude our business here and return to the battle with the Night Lords.'

'What of the Death Guard, my liege?' asked Corswain. 'Should we not simply attack, with the aid of the Iron Hands? They are known to have declared with Horus from the earliest days of the rebellion.'

'Until we can establish the loyalty of both factions here, and that of the Mechanicum as well, we should not suppose any aid from either side. The Iron Hands have been leaderless since Manus was slain at Isstvan. Who can say what their current agenda is or where their true loyalties lie? Similarly, it has been reported that those Legions that sided with Horus did not do so wholly. Whole companies and fleets have been spread far across the galaxy, and with the warp storms isolating many sectors we must not hastily pre-judge any situation, little brother. It may be the case that in Perditus, it is the Death Guard who are loyal and the Iron Hands who have turned from the Emperor's cause.'

Corswain absorbed his primarch's wisdom with a nod, while Captain Stenius took up the conversation.

'Is it your intent that we also gain position to place troops on Perditus Ultima, my liege?' said Stenius. 'Are we to break through the Iron Hands and Death Guard cordons for low orbit?'

'That is exactly my intent, Captain Stenius,' replied the Lion. 'The Invincible Reason will spearhead the thrust to Perditus Ultima, passing between the lead elements of the two enemy fleets. We shall broadcast warnings that any hostile action will be met immediately and decisively with overwhelming force. I will issue fleet instructions when we have concluded here. Are there any more questions?'

The tone of the Lion indicated that he did not expect any further debate and the assembled captains lowered to their knees to accept their primarch's command. When the others were dismissed Corswain loitered in the audience chamber, wishing to speak with his lord in private. The Lion waved for him to speak his mind.

'It is possible that what you say is true, my liege, but the likelihood of the situation is that the Iron Hands are loyal to Terra and the Death Guard are sworn to Horus,' said the seneschal. 'We should arrange our advance to favour defence against attack from the Death Guard.'

'As you say, little brother,' said the Lion. 'Yet do not be so sure in the loyalties of the Iron Hands. We are living in complex times, Cor, and there is no easy division between those who fight on our side and those who fight against us. Antagonism towards Horus and his Legions no longer guarantees fealty to the Emperor. There are other powers exercising their right to dominion.'

'I don't understand, my liege,' confessed Corswain. 'Who else would one swear loyalty to, other than Horus or the Emperor?'

'Whom do you serve?' the Lion asked in reply to the question.

'Terra, my liege, and the cause of the Emperor,' Corswain replied immediately, drawing himself up straight as if accused.

'What of your oaths to me, little brother?' The Lion's voice was quiet, contemplative. 'Are you not loyal to the Dark Angels?'

'Of course, my liege!' Corswain was taken aback by the suggestion that he might think otherwise.

'And so there are other forces whose foremost concern is their primarch and Legion, and for some perhaps not even that,' the Lion explained. 'If I told you we would abandon any pretence of defending Terra, what would you say?'

'Please do not joke about such things,' said Corswain, shaking his head. 'We cannot allow Horus to prevail in this war.'

'Who mentioned Horus?' said the primarch. He closed his eyes and rubbed his brow for a few moments and then looked at Corswain, gauging his mettle. 'It is not for you to concern yourself, little brother. Prepare the task force for the attack, and let wider burdens sit upon my shoulders alone.'

From his vantage point behind the armoured windows that pierced the central tower of Magellix station, Captain Lasko Midoa had an uninterrupted view of the whole Mechanicum complex. His attention was directed to the south and east, towards outposts Seven, Eight and Nine, currently occupied by his Death Guard adversaries. Behind the low octagonal structures spread the mirrored screens that ran the circumference of the entire facility, creating a micro-climate of thermal updrafts that assisted in keeping down the temperature at Magellix, making it inhabitable if not tolerable. Beyond were the upthrusts of Perditus Ultima's mountains, their bases hidden behind a blanket of dense greenish fog a thousand kilometres across, their summits many kilometres above the plain glistening from golden refractive materials that coated the rock.

The ever-present mist layer distorted the distances, so that although the outer stretches of the facility were several kilometres away, their bulk was magnified to make them seem almost within bolter range. Heat shimmer from the mirror wall compounded the problem. It did not help the captain's sense of perspective to know that his foes were inside the stubby keeps, ready and able to launch an attack at any moment.

With Midoa stood Captain Casalir Lorramech, commander of the Ninety-Eighth Company. The two Iron Hands officers had their helms removed, making the most of the processed atmosphere inside Magellix; for the bulk of the thirty-eight days since they had arrived on Perditus Ultima they had been in full battle gear. The pair were almost identical, with close-cropped silvery hair, broad faces and leathery skin. Only two features separated them. Lorramech had natural blue eyes while Midoa had silver-lensed inserts. Midoa also had a tracheal respirator replacing his lower jaw and throat, which hissed rhythmically with his breathing. When he spoke, his voice issued from a small speaker-comm unit set into the bone of his right cheek. The speech device transmitted Midoa's words in a sing-song cadence that was quite at odds with his mechanical appearance.

'And you are sure that they are heading directly for orbit?' Midoa asked, responding to Lorramech's report that the Dark Angels had continued towards Ultima at full speed.

'Yes, Iron Father,' said Lorramech, whose voice was deep and gravelly, each word uttered with gritted teeth and barely moving lips. Midoa was incapable of smiling at the use of the ancient honorific, but it was a source of pride that his fellow captains had chosen to raise him up to command of this expedition. 'Course and speed are consistent with an orbital heading. They will be in high orbit in less than three hours.'

'But they still have not breached the comm-dampening shell?'

'We have not yet been able to directly communicate with the Dark Angels.'

'And what of them?' said Midoa, pointing out through the window at the Death Guard positions. 'What are they doing?'

'The enemy seem intent on an intercept course,' replied Lorramech. 'With your permission, I will signal the fleet to counter-manoeuvre. We will engage the Death Guard ships and provide a screen for the arriving Dark Angels. They have two battle-barges amongst their flotilla, which would be valuable orbital support.'

'You have my permission,' said Midoa. 'We have an unforeseen and fortuitous opportunity, Casalir. Have all but one in ten squads drawn down from their patrols and garrisons and mustered in the main vehicle pool. It is my intent to launch an attack.'

'It will be as you say, Iron Father,' said Lorramech. 'With the aid of the Dark Angels, we will drive the Death Guard from Perditus and secure the Tuchulcha engine.'

It took most of the next hour for Midoa to gather together the forces he required for the counter-offensive. Squads and companies were drawn in from their positions across Magellix and the surrounding rocky plateau, moving in secret along underground highways that had been dug beneath the surface of Perditus Ultima long before the Emperor's compliance fleet had arrived.

The Iron Hands sallied forth from the main gateway of Tower Two, Predator battle tanks and Land Raider armoured carriers spearheading the thrust, while the force's Rhinos and the larger Mastodon transports followed behind the more heavily armed screen.

Almost immediately, defensive fire from Tower Eight punched through the gloom of Perditus's atmosphere: stabs of laser and the flare of heavy cannon fire. The vanguard of the column spread out into covering positions, the tanks taking up stations behind enormous scattered boulders, jagged escarpments and the shallow ferrocrete blocks that housed the station's atmosphere filtration fans. Soon the return fire of the Iron Hands was lancing into the slab walls of the outer towers, ripping trails through ferrocrete and cracking massive glassite observation decks.

Behind the storm of fire, the next wave charged onwards in their Rhinos, hatches and doors battened down as the transports roared across the undulating rocky ground at full speed. Midoa was in the lead vehicle, keen to set an example for his warriors to follow. The slower, bulkier Mastodons, each quadruple-tracked and towering above the Land Raiders, powered through the dust and fog as quickly as they could, their heavy tracks carving fresh ruts in the baked surface of Perditus Ultima.

Before they reached Tower Eight, the Iron Hands came into range of the guns at Tower Nine. Midoa had known this and speed was the best defence against the strengthening crossfire. There were three hundred metres of ground to cover where both towers could fire at full intensity, before the bulk of Tower Eight obscured the arcs of fire of its neighbours.

Being first across the killing zone had its advantages. The gunners were unable to adjust their aim quickly enough to target Midoa's Rhino, but ten metres behind him Sergeant Haultiz's transport was struck full-on by a lascannon beam. Engine boiling smoke, the breached Rhino skidded to a halt, the black-and-silver armoured warriors within spilling out onto the dusty rock while more transports poured past them. Midoa's orders had been simple: stop for nothing. The Iron Hands in the other transports barrelled past their stranded brethren, knowing that the surest way to protect their fellow legionaries was to mount an assault on the gun positions manned by the Death Guard.

The fifteen seconds it took to dash through the blazing kill zone was the longest fifteen seconds Midoa had felt in his life. He was crouched in the rear compartment with his command squad, all of them tensed and ready to extract if a hit forced them to bail from their transport even while it was moving. Over the comm, Midoa learnt of a second Rhino being hit, and then a third, but by the time the lead transports were within a hundred metres of Tower Eight's secondary gate, seven of the Rhinos and three Land Raiders had pierced the cordon of fire. A further eight Mastodons followed behind, each carrying forty Iron Hands warriors, their power fields soaking up autocannon shells and lascannon blasts with actinic flashes of energy.

As the Rhinos slewed to a halt beneath the guns of Tower Eight, Captain Tadurig and his squad disembarked swiftly, approaching the wall of the tower ahead. With them they had brought a phase field generator; a device Midoa had overseen the creation of since arriving, with the aid of his Mechanicum allies. It took only a few seconds for the Iron Hands legionaries to assemble the four-legged platform and install the phase field generator, the bulk of the machine taken up with an energy distillation dish at the centre of which were thousands of wire coils to transmit the phase field into place.

Joining his warriors, Midoa made a last few adjustments to the machine which he had painstakingly assembled and rigged from old tunnel-delvers and other pieces of warp-tech machinery left over by Perditus's previous inhabitants. They had used the channelled power of the warp as freely as the Imperium employed plasma and electricity, much to the amazement of Midoa.

With a thrum of magnetic actuators sliding into position, Midoa pulled the activation lever and stepped back. He had not yet had time to test the device he had been planning on using it during a subterranean assault on Tower Nine in a few days' time but he knew that in theory it would work. Muttering an old Medusan proverb, he waited for the power capacitors to reach full potential and then switched on the conductor coils.