A keening wail, high-pitched and several octaves above the scream of the storm, cut the air. It made Santar's head throb, despite the protection afforded by his battle-helm. Vertigo fell upon him in a crashing wave and he staggered. Impenetrable static marred the feed completely, though he could not muster his voice to give an order anyway.

Santar tasted blood in his mouth and spat it against the inner surface of his helm. He gritted his crimson teeth.

Be as iron.

Shuddering vibrations cascaded along his bones with the invasive intensity of mortar impacts. He staggered again but fought from collapsing. Fall now and he was certainly dead. No warrior wearing Cataphractii war-plate would ever rise unassisted if he fell. And there were more than just ghosts prowling the blackness. Before the aural assault, he had caught the impression of edged blades, of lithe and spectral warriors. Finding inner fortitude, Santar looked for something to kill.

Dull, armoured silhouettes stumbled through the fog his Morlocks, slow and all but mired.

Screaming scythed through his pain, a desperately mortal sound that presaged a line of bolter fire ripping along his right flank. Santar ignored it, heard the sudden air displacement to his left instead.

Found you...

Defensive instinct made Santar parry the blade blurring towards his neck, and at last he got a proper look at his attacker.

It was a mask that the eldar wore, bone-white to match its segmented armour, with a mane of tendril-like black hair cascading behind it. Judging by the form-fitting cuirass, this one was female and not a wraith or ghoul at all. The sword was long and curved, forged and sharpened by a killing mind. Hot sparks rang from the blade as it ground against Santar's lightning claws.

She was at once a part of the storm yet at the same time apart from it, blending with the eddying wind as she chose. Leaving a trail of jagged spikes to fade in the air behind her, she disengaged.

Santar kept his guard up, ignoring what his retinal lenses were telling him and trusting to instinct. When the follow-up attack came it was delivered with power. The sword clashed against his lightning claw and he felt the jolt of it all the way up into his shoulder. She glared at Santar, incensed at his defiance, and released a hell-screech from her mask that forced the first captain's jaw to lock. Weathering the aural barrage, he thrust with his other lightning claw and trapped the eldar's bone blade fast.

A pistol appeared in her other hand but the shots rebounded harmlessly off Santar's war-plate like ineffectual insect stings.

The grating laughter emitting through his mouth grille surprised him.

Abandoning the pistol, she took her sword in a two-handed grip in an effort to release it. Whilst trapped she could not withdraw and if she disengaged without her blade she would be cut apart. Even eldar were not faster than lightning.

'You're not so scary,' Santar grunted through clenched teeth as she fed another hell-screech into his face. The first captain's superior strength was telling against the alien's pressing sword, and his bionics growled in anticipation of triumph. 'I am scarier.'

Santar parted her weapon in two, shredding it with the scissoring action of his paired lightning claws. The sundered half of the blade, separated from the ragged edge of its broken hilt, spun into the warrior's undefended chest and impaled her. She fell back into the storm and was immediately lost within it.

The ambush was faltering, and Santar was certain the darkness itself was receding as the storm ebbed. Several Morlocks lay prone where they'd been transfixed by blades or felled by the howling but others were rallying. Even the feed was returning to normal.

'Are you alive, first captain?' It was Desaan, the muffled thud-chank of his bolter chorusing behind him.

'Alive and wrathful, brother-captain,' Santar replied, gutting another of the wraith-warriors. He was wrenching the blades free from her back with a satisfying slurrch of flesh when his left arm seized. He tried once to free it but it wouldn't move.

'Something is wrong. Brother, I... gnn.' Paralysis anchored his bionics in place as if they had simply stopped functioning. His legs, also mechanised, were locked. 'I cannot... gnn,' the pain of it was incredible and he gasped the last part, '...move.'

Searching for allies he only found two fleshless masks bearing down on him. They grinned cruelly, a witching glow to their features, and spat something vengeful in their native tongue.

'I can kill you both... one-handed,' Santar promised but felt a chink in his confidence as they began to weave around him.

Something was coming through the comm-feed, arresting his attention from the wraith-warriors as they closed. He recognised the plaintive cry of his fellow captain.

Between the circling forms of the eldar, he glimpsed Desaan stumbling through the darkness, firing wildly. An errant burst clipped one of the other Morlocks, dropping his guard so another wraith-warrior could plunge its sword between the armour joint linking breastplate to greave. The Iron Hand sagged before the storm cut him off from view.

'Desaan!' Santar's would-be killers were near. 'Watch your fire, brother.' He couldn't afford to be distracted. Desaan staggered on, bolter tracking dangerously as his firing arcs went unchecked.

'Desaan!'

He looked as if he was...

'Blind, first captain...' he mumbled, stunned. 'Hnn... I can't... see...' His arm was limp by his side. Others were afflicted too, the Morlocks undone by precisely what had given them strength.

Flesh is weak. The mantra came back to Santar with mocking irony.

The eldar had done something to them, crafted some malign sorcery to affect their cybernetics. To a man, the Morlocks all had extensive bionics.

Santar stared at the wraith-warriors who were brandishing their swords in the promised cuts to come.

'Come on,' he slurred. His heart might as well have been bared to their blades.

The wraith-warriors paused, lingering half-corporeally amidst the storm. As one they blurred. Two became many, and their harsh laughter resounded through the howling that was pounding Santar relentlessly.

'Come on!' he roared. 'Fight me!'

The eyes of one or was it all? narrowed behind its mask and Santar followed its gaze to where his arm was paralysed. Only it was moving again, but not of the first captain's volition. Energy cracked along the lightning claw blades, fierce enough to rend war-plate. Fascination and disbelief coalesced into horror as Santar realised they were being turned inwards... towards his neck.

He clutched his rebellious wrist, held it with his other hand whilst the alien laughter grew into a tinnitus drone. Sweat beaded his face as the muscles in his neck and shoulder bunched with the effort of trying to restrain the foreign limb that was trying to kill him.

Slain by his own hand, there was no honour in that. It was a despicable death, and the eldar looking on knew it.

'Throne...' he gasped. Even the squeal of the bionics sounded different, belligerent somehow.

Fight it! he urged, but the link between machine and flesh was far from symbiotic. One was almost regarded as a contagion to the detriment of the other, but now that boon had rebelled and become a curse.

The actinic smell of scorched metal filled his rebreather as the energised blade tips touched the edge of his gorget. Santar estimated it would take a single, determined thrust to pierce the armour and tear open his neck. At most he had seconds.

Santar was hoarse from his roared defiance but his struggles were lessening.

He closed his eyes and his voice shrank to a whisper in the face of the inevitable.

'Primarch...'

Ferrus was alone; there was only him and the storm. He had since donned his war-helm but saw no evidence of his Legion on the retinal display, so did not waste his time calling out to them. The last contact he'd had was from Gabriel Santar, a desperate plea for them to stay together.

Onwards, drive onwards.

The compulsion was too strong to resist. They were deep into it now. Whatever horror this desert was harbouring, whatever cruel truth he had been summoned here to witness, he could no longer deny it.

This was no ordinary storm. Too redolent with the fabric of his dreams, it was awash with metaphors from his violent past and the figurative snares of his possible futures. He heard voices on the scything wind but no sounds of battle, no war cries.

I expected a battle.

Ferrus could not discern their meaning but sensed their words were important.

The comm-feed was down. Not even static haunted its channels. He accepted that too, and kept moving. Whatever this was, whatever destiny or sliver of fate had delivered him here, he would meet it head-on.

Eyes... slits like those of a serpent, watch me. I can hear the sibilance of its tongue like a knife on the breeze. It is the same knife I feel resting against my throat.

A memory surfaced.

After leaving the landship, he had spoken to Mortarion again, or rather his brother had spoken to him. The other primarch had left him with a barb that Ferrus could not easily forget or silence.

If you are not strong enough, he had said. If you cannot finish it alone...

'Help me?' he roared into the uncaring storm. The wind was mocking in reply. 'I need no help.' He laughed, a cruel and terrible sound. 'I am strong. I am the Gorgon.'

Ferrus was running, though he couldn't remember quickening his pace so drastically and without cause. But he ran as hard as his limbs would allow. The darkness of the sand plain only seemed to lengthen as earth and sky merged into one.

'You cannot help me,' he raged as a sensation of flying then falling overtook him.

And in a much quieter voice, lost to his subconscious, '...no one can.'

Two legionaries stood out on the golden sand bank, staring into a pall of darkness.

In front of them, the black cloud surrounded the Morlocks like ink on water.

Bion Henricos could scarcely believe what his eyes were telling him and wondered if his augmetically enhanced brethren were seeing the same.

'What is that?'

Brother Tarkan widened the aperture of his bionic eye, enhancing its focus with minute movements of his facial muscles. Every adjustment produced the same result.

'Inconclusive.'

'Nothing natural,' Henricos replied, rising from a crouched position.

Until he regrouped with Captain Meduson, one half of the battalion was his. Whatever the blackness was in front of them, he would have to deal with it on his own. He had tried opening the feed, but the link was foiled by whatever psy-storm was boiling in the desert basin.

'It has claws, brother-sergeant,' said Tarkan.

Two hundred and fifty legionaries, just a portion of the Iron Tenth, awaited Henricos's command. Bolter-armed and full of fury, yet here they were, stopped in their iron tracks by the dark. A pity they did not have any jetbike divisions to circumvent the storm and assess it more fully. Not for the first time, Henricos considered the lack of tactical flexibility in the Legion.

'That it does,' he said, scanning the horizon and the pillared rocks overlooking the shadow-choked valley. He was close enough to touch it and reached out with his iron hand. A tendril of swirling sand tinked harmlessly against the metal and as Henricos lifted his gaze he found what he was searching for above the storm. It orchestrated the darkness, a tall, thin figure in dun-coloured robes. It carried a witching stave, carved with alien runes and inlaid gemstones.

'Brother Tarkan,' he said in a grating cadence, thick with promised retribution, 'remove that stain.'

Tarkan was a sniper, part of one of several such squads in the Tenth, and he handled his long-barrelled rifle with a marksman's grace. It was fashioned for his hands and carried a scope-sight that would connect to his bionic eye and forge an infallible link between firer and target.

Looking down the scope, Tarkan lined the green crosshair over the witch's helmeted head and fired. The expulsion of the shell rocked the weapon but Tarkan had compensated for that already. Still tracking through the scope, he grinned with mirthless satisfaction as the alien's cranium burst open and it fell from the pillar without a head or much of its upper torso.

He slung the rifle onto his back.

'Target eliminated, brother-sergeant.'

Henricos raised his fist and the rest of the half-battalion marched onto the bank.

There was no sense in holding back at this point.

'Forward, in the name of the Gorgon.'

Together two hundred and fifty warriors waded into the dissipating storm.

Something repelled Henricos as he entered the shadow. It was a stiffening of the mechanisms in his bionic hand, clenching it into a fist when he desired it to be loose and ready to unsheathe his blade. He forced it open as he closed on the stricken Morlocks, unclear as to its malfunction, and halted when he saw what they were doing to one another.

One legionary had his own eviscerator lodged in his armoured chest. The teeth were red and churning. With one hand he was trying to prevent the blade from sinking deeper, but the cybernetic one was pushing it farther into him. Another lay prone and unmoving, his helmet staved in by his own power-maul. Crimson fluid was leaking from the cracks and pooled around his head. Some staggered, half-blind, or were rooted by bionic legs that would not function. Bionic hands wrapped themselves around throats of flesh and choked the life from their bearers. Grisly and terrifying, the evidence of machine-carnage was everywhere.

The virtue of the Iron Hands' creed was being turned against them.

Henricos's momentary pause was born out of self-preservation for his half of the battalion and a desire not to make a grievous situation worse, but whatever malady was afflicting the Morlocks hadn't seized the Iron Tenth yet.

'Captain!' Henricos barged into the storm with renewed vigour. Behind him, his brothers fanned out, interceding where they could, stopping the self-mutilation from escalating any further than it already had.

'I see it!' Meduson replied. 'By the Emperor's sword, I see it... Bring them down, brother. Save them from themselves if you can.'

The link went dead, the reprieve in communication only fleeting, just as Desaan blundered into Henricos's eye line.

A jagged combat blade was gripped in the captain's cybernetic hand as he wrestled with some unseen assailant that was trying to ram it into his face.

Henricos reached him as the monomolecular knife was about to pierce flesh.

His iron fingers clenched around Desaan's wrist, holding it steady.

'Hold on, brother!' he cried, trying to bring the weapon under his control. As he struggled, Henricos saw faces inside the darkness. They were swift and incorporeal, like snatches of freezing fog given spectral form. A line of bolter fire chased one but the ghost dissipated before it could connect. A mocking, howling chorus followed that set the sergeant's teeth on edge.

Desaan's voice was pained. 'Bion, is that you? I cannot see, brother.'

His visor was dark, like an iron blindfold wrapped around his eyes.

'Fight it, brother-captain!' Henricos urged, but Desaan's bionic strength was incredible. Even together they were losing and the blade slipped a little closer, piercing flesh.

'Gutted by my own combat blade,' said Desaan with a pained grimace. 'Not as glorious as I'd hoped.'

'You're not dead yet,' promised Henricos. 'Lean back...'

Letting go of Desaan's arm, he wrenched out his Medusan steel-edge and fed power into the blade. It took several seconds longer to draw than it should have, his iron hand resisting him.

Soon it will take us too.

'What are you doing?'

'What I must.' The shriek of hewn metal eclipsed the howling as Henricos began sawing off the captain's forearm.

As well as he could, Desaan tried to stand his ground and be still.

'If you slip...' he growled, teeth clenched.