Karael stood quiet in the juddering darkness.

The restraint harness fastened him in place, crimson overheads the only light source in the drop pod’s cramped confines. Flak bursts popped and thudded beyond the petal-doors, sharp intakes of breath in the hateful shriek of their descent. The Dark Angel checked his bolter’s ammunition count, teeth gritted in a wolfish grin.

‘We have come,’ his brothers whispered. ‘We are death.’

Adrenaline fired Karael’s blood, blending with the chemical cocktails administered by his battleplate. The whisper resolved into a chant, a statement of intent, growing in strength and surety like a cyclone gathering its power moments before touchdown.

‘We have come. We are death.’

Orbiting warships broadcast it to every active Cthonian vox-frequency and data-net. Librarians saturated astropathic ducts with it, risking their sanity so the warp itself screamed their oath and Horus’ honourless traitors would know who came for them.

The Dreadwing were not shy about their purpose.

‘We have come. We are death.’

Karael held his silence. He was a postulant, his void-black armour bare of heraldry beyond the winged sword and the battle honours inscribed on his greaves. He had not earned the right to voice the chant or wear the skull-in-hourglass. But that did nothing to curb the grim pleasure he took at the prospect of exterminating Horus’ mongrels.

‘Brothers, the glass is turned.’ Lieutenant Annael’s voice cut through the chant like a whetted blade, hatred barbing every syllable. ‘Let the grains fall.’

The drop pod slammed into the ground, its impact jarring Karael’s bones. He hammered his restraint harness’ release. Tanis, the Interemptor opposite him, triggered his own release and hefted a plasma burner, its coils glowing neon blue. Bullets and las-bolts sparked against superheated ceramite, the cooling hiss muted by environment seals. He murmured a vow to the Lion and raised his bolter. Release charges popped.

Sickly grey light washed into the pod.

‘We have come!’ the Dreadwing roared. ‘We are death!’

Karael emerged, firing.

His first kill was a Legion serf in padded flak armour, Horus’ slitted eye daubed gold on the breastplate. Mass-reactive rounds bisected him. Two more pitched sideways from his second volley, ribcages blown open, shredded offal evacuating messily onto the street.

Gouts of ionised plasma hissed from Tanis’ weapon, his fire blending with the other Interemptors of Squad Derwyn as they reformed. Traitors vanished in wheezing puffs of ash or detonated in fleshy plumes from Karael’s bolts.

‘Secure the landing zone.’ Praefectus Derwyn’s voice was a mess of tics and whirs, his throat and torso entirely reconstructed with augmetics. ‘Second wave inbound.’

‘For the Lion,’ Karael echoed the squad’s affirmation.

He ejected a spent magazine and slapped a fresh one into place. The Interemptors fanned out across an open area surrounded by squat habs and dilapidated tenements. It had been a residential sector millennia ago. Cheap plastek frames were split and bowed, riddled with bullet holes and faded scorch marks. The enemy swarmed towards them, taking firing positions behind collapsed walls and in abandoned residences.

They chanted.

The words carried over crashing bolters and autoguns, the venomous hiss of plasma discharge, the fatty sizzle and wet wrench of violated flesh. Bullets and las-bolts hissed and snapped against his armour, scorching thumbnail-sized dents into it. He paid them no mind, fury misting any rational thought. Vox-horns boomed the words through gargoyle-mouthed grilles. They dragged grief and pain from the iron curtain he penned them behind and set him snarling like one of Angron’s beasts.

‘The Emperor is dead. The Emperor is dead.’

Karael strode into the fire, undaunted, his bolter’s targeting systems slaved to his retinal feed. Reticules swamped his vision, each locked onto a different irritant. A bullet bit into the joint ribbing between his pauldron and plastron. His bolts shredded a Cthonian ganger with snub-pistols, the armour’s sensorium screeding bio-analytics beside reticules in serifed script that sizzled away with each kill. Two men fell apart like rotten meat. His chainsword decapitated a young woman with eight-pointed stars branded into her cheeks.

It was not enough. It would never be enough.

‘Where are the Sons?’ one Interemptor, Mathias, growled. He tossed a rad grenade into a clutch of traitor Auxilia. Its detonation scorched armour to dust and reduced mortals to weeping, shambling horrors of liquefying flesh and muscle.

‘Focus on the enemy,’ Derwyn clicked. ‘Second wave due in one minute.’

Karael grunted his agreement, disembowelling a renegade Cthonian headhunter with a lazy sweep of his chainsword. He cut both arms from a ganger with diamantine-tipped drills instead of forearms. A heart shot obliterated him. Karael mag-locked his chainsword and reloaded, wincing when an Auxilia officer’s powered blade clipped his side. He crushed the woman’s throat, fear and breathlessness bulging her eyes as her skin purpled.

The Dreadwing advanced, utterly relentless.

They shrugged off small-arms fire, blood and lubricant dribbling down void-black plate where a joint was pierced or cabling damaged. Rad-missiles scoured habs and tenement flats with lethal shards. Sunfire bursts from plasma burners and Mathias’ plasma incinerator vaporised traitor soldiers and reduced vehicles to shimmering pools of radio­active slag. They would let nothing live, and Karael relished such purity of purpose.

It did not stop the chant.

‘The Emperor is dead. The Emperor is dead.’

It boomed from the vox-horns, the speaker-servitor’s flat and charmless warble more animated than any Karael had heard before. It was the death rattle of those Guard traitors and Cthonian gangers dull-witted enough to contest the Dreadwing’s landing. His chainsword tore every throat that forced the words between bloodied lips, impaled every heart that did not repent their treachery in their final moments. It seemed an endless task.

‘Can we not put an end to that filth?’ he asked.

Derwyn crushed a mewling ganger’s head beneath his boot.

‘No,’ he clicked, wiping blood and bone fragments onto nearby rubble. ‘That is not our task, postulant.’

Karael nodded and executed a chem-bulked ganger whose sweat reeked of combat narcotics. His ears pricked at the piercing whine of descending turbines. He turned to watch four Stormstrikes escort a gilt-edged Stormbird towards the landing zone. Gunships streaked through flak-strewn skies, delivering Dark Angels into battle against the traitors. A handful fell, but many made it through.

The Stormbird’s ramp dropped.

Annael disembarked before the engines had finished cycling down. The lieutenant, a close confidant to Marduk Sedras, wore Cataphractii warplate edged in Martian red-gold, the winged sword emblazoned on the breastplate and greaves in glittering garnet and alabaster. The Dreadwing’s sigil was worked into their pommels, rendered in chips of pure jet. A cream tabard snapped in the wind and silver chains suspended censers and ornamental keys from his waist.

His Naufragia followed him, each Terminator clad in Cataphractii warplate, plasma blasters raised and Calibanite warblades trailing lethal energies. Two Interemptor squads followed them, the bone-coloured plates amid the void-black denoting veteran status. They escorted a matt-black cuboid the height of a Space Marine. Gravitic impellers moved it on a shimmering cushion of energy and a silver box was mounted on one face.

‘What is that?’ he voxed, the chant forgotten.

‘I do not know,’ Mathias replied first.

‘The Dreadwing’s arsenal holds relics of the Unification Wars,’ Derwyn said. Karael did not like the evasion in the synthesised voice. ‘The Emperor granted the Six Hosts of Angels many unique weapons later forbidden to the other Legions.’

‘Remember Praefectus Derwyn was a warrior once,’ Tanis said, his humour strained by the enemy’s repeating chant. ‘He was not always a battle-servitor sheathed in ceramite.’

The other Interemptors laughed and Karael’s lips pressed into a thin smile. It was an apt description, but both displays of mirth were equally forced.

‘Knowledge is not your burden, postulant,’ Annael said, his helm inclined in greeting. The Terminators strode past, as did the Inter­emptor veterans. Karael fell in with Derwyn’s squad, forming an honour guard to the cuboid. ‘Nor yours, Brother-Interemptors. Remember that knowledge accompanies experience as if it were its shadow.’

He knew the axiom as well as any son of Caliban. It was from The Verbatim, the primer text for knights of the Order and Dark Angels aspirants. That lesson stressed skills and knowledge be passed to knights when experience determined they were ready, a trait that found its mirror in the First Legion’s secret hierarchies and hidden orders.

‘Aye, lord,’ Karael said, sullen but respectful. Derwyn and Annael were the two officers assigned to determine his worthiness for the Dreadwing. ‘Forgive my impertinence.’

The Dreadwing stalked over the rubble. Ferrocrete chunks threaded with twisted lengths of rebar crumbled beneath their tread. They strode over bodies, several still alive, ignoring the grasping fingers that reached for them. Karael put a bolt in one woman reaching for a shot-cannon, the action instinctive rather than considered.

‘You showed none. It is simply a lesson worthy of remembrance,’ Annael said. ‘I see there was some opposition to our landing, Praefectus. Nothing too troubling?’

Derwyn’s synthesised laughter wheezed across the vox.

‘No, lord,’ he grated. ‘Some Cthonian citizens wanted to express their dissatisfaction. We noted their complaints before they were illuminated.’

They wheeled right, following the Terminators east towards the industrial sector. The device turned with them, clumsy in its movements. Shadows darted through the ruins. Karael signed Mathias. The Inter­emptor nodded and passed word along. It was not hard to smell an ambush, but if the enemy were setting one, the Dreadwing would be ready.

‘I expected nothing less, brother,’ Annael said. ‘It is precisely why I requested your squad for this duty.’

Karael’s aural receptors caught snippets of shouted orders and bolter fire. They were of little interest. The device was another matter. It carried no biological or radiological indicators, or warnings of any kind, only a steel box with a small screen and several haptic controls. Anonymity gave it an ominous air.

‘And what is our duty, lord?’ Derwyn clicked.

‘Castigation, my brother,’ Annael answered. Eagerness bled into his voice and Karael smiled reactively. Ignoring the concern tugging at the back of his mind, he clutched his bolter tighter. They turned again, marching along a street lined with plastek habs. The shadows vanished, all signs of ambush with them. ‘We escort the device to a manufactorum on the sub-level, prime it, and withdraw for extraction. Today we are angels of vengeance, striking a blow the Warmaster and his mongrel-blooded sons will never forget.’

‘Is that why we are on a separate channel, lord?’ Mathias asked.

‘This duty must be secret from all not assigned to it, hence this channel’s vermilion-grade chimeric encryptions,’ Annael said. Karael suppressed his surprise. Such encryptions were rarely used, and the idea of clandestine assignments kept from other Dreadwing was an equal surprise. ‘Secrecy is essential to success. Priority transmissions will penetrate, but we are not to respond. We are also to ignore any distress calls received.’

‘What of the Fists, lord?’ Derwyn asked.

‘Fleet augurs detected no Seventh Legion transmissions,’ Annael said, too quickly for Karael’s comfort. ‘They must have fallen, along with any who stood beside them.’

They continued their march in silence, through streets crowded with cheap plastek habs and tenements supplanting older structures of quarried stone. Their weapons covered every potential firing angle and the Dark Angels turned wherever Annael gestured with his Terranic greatsword. The Naufragia wheeled behind him like a murmuration.

After twenty-five minutes, they entered the fringes of an industrial sector. Tenements and habs ceded to sheet-metal refineries and storehouses. They passed between rusted drums and open containers, noting each one had been picked clean of resources and materiel. As a Dark Angel, Karael had walked on dead worlds and through cities long fallen to ruin. None of them made him uneasy. Cthonia did.

They found the sub-level access scant minutes later.

It was a simple set of stone steps, framed by ferrocrete walls, worn smooth by age. Smashed lumen-strips and glow-globes meant the steps vanished into the darkness. Even the enhanced visual spectrums of his battleplate could not pierce the gloom.

‘Is this the only sub-level access?’

‘No, Praefectus.’ Annael led the way, thudding into the gloom at the head of his Terminators. Their cowl-lumens bobbed in the dark. ‘It is isolated, emerges a kilometre from our target and its lack of technology reduces potential for enemy interference.’

Karael followed Derwyn and his Interemptors into the dark. The walls were pitted and cracked, veined by moss. The legionaries’ heavy tread was a black echo that dogged their descent. The low hum of the device’s gravitic impellers grew strained on the difficult terrain, reducing their pace almost to a shuffle. They walked dark, dank and cramped tunnels for over ten minutes, doubling back three times to find accesses wide enough for the Terminators.

He breathed quiet relief when they emerged onto a walkway carved into the rock face at the edge of a cavern. Refineries, storehouses and shanty towns dominated the sub-level, the buildings over thirty metres beneath him. He spotted the manufactorum immediately, an ingot of black iron and a clear precursor to the belching monstrosities the Mechanicum now erected. A small hangar adjoined the warehouse space and metal shacks clung to its side like rusted barnacles. Annael was right. It was barely more than a kilometre away.

The Dark Angels continued their slow descent. Karael’s eyes and iron sights flicked between windows thick with cobwebs and narrow defiles cut between buildings. Static teased him with fragmented sentences and mismatched words. They were too deep to hear their brothers on the surface and it could easily be enemy vox traffic.

The beating of his hearts quickened and his battleplate squirted fresh stimulants into his blood. They were entirely too exposed on the walkway. The last few minutes of their descent ticked by with Karael’s blood thundering in his ears, alert to the possibility of an ambush, his breath infused with the rich chemical taste of adrenaline. They reached the bottom unharmed.

Then the Sons of Horus opened fire.

Two Interemptors died in the first salvo, their torsos riddled with detonations. Reavers launched themselves from a refinery’s dusty skeleton, chainblades snarling and pistols flaring. Another Interemptor fell, his head vanishing in a crimson fountain, and bolts spiralled fractures through a Naufragia’s breastplate.

‘Close ranks!’ Annael bellowed. Tendrils of disruptive energy wreathed his Terran blade and power fist. The Naufragia withdrew into a circle and fired, coring two Reavers with darts of blue-white plasma. ‘They must not reach the device.’

He sent three bolts into a Reaver chieftain with Horus’ planed features. Blood and bone sprayed across his brothers. Bolter fire cut down two Sons wielding glittering powerblades. Plasma speared Mathias, forcing him to his knees. His life signs flared. Karael loaded a fresh magazine. He suspected Mathias had lost a lung. The Dark Angel fired on the Reaver wielding the plasma pistol. Bolts split ceramite and blood burst from the traitor’s ruptured chest. Static teased a Legiones Astartes voice and slices of words that meant nothing.

Karael’s pauldron cracked under a sustained pistol barrage, pain knifing into his shoulder. His bolts cut through the air, punching fist-sized craters in a Reaver wielding a crackling power fist, its knuckles slick with blood. Karael drew his chainsword, parrying a strike towards his primary heart, and launched a feint that merged into a thrust. The vox crackled live, the faint voice dripping chained frustration from a Necromundan accent.

‘…of the Seventh Legion. We are under attack and require reinforcement. All surviving Imperial forces, this is Vatrenus of…’

‘The Seventh?’ Mathias groaned, picking himself up. ‘They live?’

The Reaver blocked and launched a counter-attack at Karael’s throat. He sidestepped the blow, his blade punching through the Reaver’s gorget seal. Blood and diced meat spat from the whirring teeth. He dragged the blade free, raising it to block a decapitating strike from a second Reaver. He deflected a blistering series of blows, feinting and launching counter-ripostes, exercising his duellist’s patience until the Son over­extended himself. He drove the blade into the earth, cutting the Reaver from nape to groin.

‘They must be desperate,’ Tanis said, his words punctuated by the hiss of vented gases. ‘I fought three compliances alongside them. Not once did they request aid.’

‘Forget the Seventh!’ Annael roared, his power fist obliterating a Reaver’s torso. A Terminator fell, hacked apart by Cthonian blades. ‘Protect the device. Shield it with your lives, brothers, ere the vortex consumes us all.’

The bottom dropped from Karael’s mind.

Bolts snapped from the mouth of his weapon, cutting a Reaver’s torso and head apart. His blade decapitated a Son that oozed viscous black liquid from his knuckles. He could not reconcile what he had heard with reality. Vortex weapons were the most dangerously potent archeotech ever conceived by humankind. They did not destroy through explosive yield or bio-engineered toxicity. They ripped reality open, dissolving everything in raw warp matter.

Karael’s distraction nearly cost him his life.

A bareheaded Reaver lunged, his chainaxe’s whirring teeth devouring the empty air towards Karael’s neck. Karael parried the blow and smashed his chainsword’s knuckle-guard into the Son’s nose and jaw. Bone snapped and blood spurted. The Reaver’s off-hand flashed silver, carving a smoking rent in Karael’s breastplate. Pain lanced through him and blood wept from the tear. Breath sawed between his teeth and sweat rimed the inside of his gorget seal and dappled his close-cropped beard. He threw the Son of Horus back.

Around him, Reavers threw themselves at the Dark Angels with renewed zeal, their numbers slowly whittled down. The Sons of Horus fought like cornered Great Beasts, twice as cunning and three times as dangerous. He was surprised there were so few. The other Dark Angels must have had them distracted.

As the Reaver came at him again, desperation and fury seeded the warrior’s eyes with burst blood vessels. He swung at Karael’s neck with his combat blade. Karael blocked the strike with his forearm, ignoring the thunderclap of ceramite, the hot kiss and crisp of flesh against a disruptor field. The Reaver’s axe swung down to cut diagonally across his body. Karael blocked with his chainsword and headbutted the Reaver, pulling his blade down to cut the traitor from clavicle to pelvis.

He looked around. The other Sons were dead, joined by nine Interemptors and three Naufragia. There was no Apothecary to extract their progenoids, nor could they vox for one. Shame burned in his chest. The fallen would die twice today.

‘We move,’ Annael said, regrouping his Terminators. The other Dreadwing limped into formation, blood weeping from ragged holes in their battleplate. ‘We cannot linger, or assume they are alone.’

‘What of the Fists, lord? And our brothers, their legacy…’ Karael began.

‘Their legacy will be the Emperor’s vengeance against the traitors,’ Annael said flatly. ‘We can do nothing for the Fists. The mission takes priority over all other concerns.’

Karael glanced at the vortex weapon, disgust blooming.

‘We cannot dishonour their sacrifice.’

‘Your vacillation does that well enough.’

Karael recoiled as if slapped. Words fell from his tongue.

He joined his brothers, unable to shake the thoughts of the dishonour inflicted on their fallen, certain that his hesitation had been noted. The Dark Angels advanced through the cramped warren of underhive streets and shanties. They crashed through shacks that barred them from quicker routes, shielding the vortex weapon with their armoured bodies. Karael still struggled to believe it was a vortex weapon, its ominous air worsened by context and the knowledge that it would be used against friend and foe.

They were First Legion. The Dark Angels. They did not turn upon allies or slay indiscriminately. That was the province of Mortarion’s ghoulish footsloggers and Perturabo’s sour ditch-diggers. It was not the behaviour of a knight of Caliban.

Karael’s silence turned sullen as Vatrenus repeated his dour plea. It cycled through the vox less than a kilometre from the manufactorum hangar, punctuated by the rolling crash of bolters and the fizzle of lasweapons. The Dreadwing brothers seemed unaffected, their focus on shielding the dread device from falling debris and traitor fire. The enemy was chanting again, audible over Vatrenus’ vox-link. Nausea threaded itself through the acidic burn of Karael’s burgeoning shame and anger.

‘The Emperor is dead!’ they jeered. ‘Dead. Dead. Dead!’

Karael matched his brothers’ increased pace. Their silence became a taut thing of simmering fury and strangled grief, their desire to punish the traitors a physical sensation that pressed against his skin. They had failed to reach Terra in time to protect the Emperor; instead they could only punish Horus’ followers for their betrayal. Karael refused to believe He was dead, but the sheer powerlessness was utterly alien. It made his skin crawl. The cold, dry air stank of desperate fury, with Vatrenus’ voice and the traitors’ chant shadowing every step.

‘We cannot ignore them, brothers.’ The words slipped through gaps in his gritted teeth and breached the thin crease of his lips. He was grateful to be on a private channel. ‘It would shame the entire Legion if it were known we had abandoned our cousins.’

The Dark Angels jogged across the perimeter, under empty promethium towers and hunched loading cranes. They crashed into the hangar through a corrugated steel door sized for ground haulers, ignoring the dusty signs for logisticae offices, assembly floors and workers’ quarters stencilled on the wall. Grey light spilled from the retractable roof overhead, a narrow cleft in the cavern ceiling visible through the aperture.

‘We can do nothing for them,’ Mathias said, sweeping one corner of the hangar clear. Steel containers, sternum-high on the legionaries, had been emptied and left to rust. ‘We are knight-castigators, the Lion’s sanction. Leave heroics to the Deathwing.’

‘The cause is paramount,’ Tanis agreed. The hangar secure, the Interemptors fell back into small knots while Annael and the Naufragia attended to the device. The lieutenant keyed a sequence on the haptic controls. ‘It matters more than our brothers’ lives, and ours.’

‘What of our honour?’

‘It matters more than notions of honour and our brothers’ perceptions,’ Tanis continued. ‘Honour is a sacrifice all Dreadwing make. We sully our hands and blacken our souls with dishonour in the Lion’s service and the Emperor’s name, performing the duties that others cannot, or will not.’

Karael disabled the private vox.

‘Lieutenant, may I speak?’

‘Freely,’ he said, still hunched over the control panel. His scowl was plain in his voice, but Karael was determined. He would not abandon his brothers.

‘Should we not alter our extraction plan, or issue a warning to the Seventh? There are no reinforcements, and our orders must permit some latitude.’

‘We are angels of darkness and vengeance, postulant, not mercy.’

‘The Fists served with loyalty and honour.’ Karael leashed the anger threatening in his voice. ‘They do not deserve the fate you hand them.’

‘Casualties of war.’ Annael raised himself to his full height in a snarl of strained armour servos. ‘Regrettable but necessary.’

‘They are our brothers,’ he said. Guilt worked his tongue and vocal cords like a maestro. It was unbearably pathetic. ‘Honour and brotherhood define the Legiones Astartes, a definition the Warmaster’s perfidy should make more important, not less. If we leave the Imperial Fists to die, are we any better than he?’

‘Your idealism is commendable, brother,’ Annael said, a muted vox-click sealing them in a private channel. Begrudging respect crept into his tone. ‘Those qualities should define the Legiones Astartes, but these are unkind times when they cannot interfere with our duty. Perhaps there will be a day when the Dark Angels can once more define themselves in this way, but that is not today. The decision is made. We will not aid the Fists.’

Annael closed the channel before he could reply.

For one laughable moment Karael thought he had scored a point. He looked to Derwyn and the eight surviving Interemptors of Squad Derwyn. They showed no concern for the Imperial Fists, or their hand in the deaths of loyal kin. They repaired damaged plates with armour cement and checked their weapons. Perhaps it was as Tanis said. Perhaps it was a familiar burden. Their behaviour possessed hallmarks of orthodoxy.

Shame was a Nemochian serpent that thrashed free of every bond he placed on it. He would be culpable for loyalist deaths through inaction, a violation of his oath as a Legiones Astartes warrior, but warning them would violate his oath to the Dreadwing.

He racked his brain for a way to satisfy both oaths. Neither could be twisted to suit the other. Karael was a Dark Angel, not a Word Bearer, to whom oaths were malleable and inconstant. His skull throbbed, a dull pulsing pain, but resolution remained elusive. Vatrenus broadcast again and Karael disengaged his vox’s security protocols.

Postulancy be damned.

‘Vatrenus. Do not hold position. Devastation comes. Withdraw.’

He closed the link and re-engaged the security protocols. Annael’s seething breaths were the bass rumbles of a Calibanite lion. His voice was threateningly low, his anger cold and smouldering, more insidious than a raging inferno. Karael met the glowering eye-lenses, ready to accept the consequences.

‘What did you just do?’

‘I kept my oath as a legionary,’ he said evenly. ‘I could not allow the Fists to die.’

‘Your oath as a legionary,’ Annael repeated, tasting the words. Incredulity stained his tone when he repeated them again, spicing them with a bleak, bitter humour.

‘I am oathed to this mission, but not yet to the Dreadwing. My Astartes oath is made to the Emperor, and I could not violate it through my inaction.’

‘The Imperial Fists failed the Emperor,’ Annael snarled, his facade of discipline and devotion to the mission falling away. ‘If He is dead, it is because Dorn and his dull-witted Legion failed to protect Him. These warriors could not even cleanse Cthonia. They may be complicit by their failure, and they should die because of it.’

‘You knew they were here,’ Karael said. It was not a question.

‘It matters not what I knew,’ Annael spat. ‘Knowledge is a burden borne by those capable of bearing it. Ignorance is a shield for others to cower behind.’

Karael said nothing. There was nothing to say.

‘We must now defend this location and await extraction,’ he said, turning to his officers. ‘Barachiel, use this installation’s vox-relay to implement the alternate extraction. Tharahel, form these containers into a viable defensive line. Derwyn, your squad and the remnant of Dumah’s will form our outer line.’

His brothers were quiet as they carried out the instructions. Anger bled from them, but there was also a grim relish for the blood yet to be spilled. The Dark Angels settled into firing positions, and Karael hoped the Imperial Fists had received his message.

Annael’s parting words rang in his ears.

‘If you have any honour, you will embrace the penitent’s fate.’

The Sons of Horus attacked twenty minutes later.

They stormed forwards in a wave of ceramite and muzzle flashes. Assault Marines sprang forward on screaming jets. Reavers were a black knot howling tribalistic war cries and revving their chainblades. A Contemptor strode beside them, the ground trembling with its every step. One arm sported a long-barrelled assault cannon, the other a quartet of wickedly curved talons. Karael’s lip curled. He drew aim on a Reaver and fired. The traitor’s skull detonated in fronds of blood and bone.

Return fire clanged against containers and split ceramite. Karael staggered backwards, his breastplate cracked. Pain lanced through him. He dismissed the red alert-runes, wounds already clotting. Bolts punched through a Son’s gorget. The traitor stumbled, blood spurting between armoured fingers. Bolts and plasma ripped through the enemy ranks, and armoured bodies pitched forwards, a storm of scattered limbs and ruptured plate. Karael shifted his fire, a mass-reactive burst blowing a heretic’s head apart.

The Contemptor opened fire.

Three Interemptors toppled backwards, their signum-runes fading from his retinal feed. Another collapsed, one arm severed by bolter fire. It dripped sparks and stringy tissue, flapping uselessly at his side. He fired his plasma burner one-handed until a bolt cratered his faceplate. Rad grenades exploded amongst the Sons, shards biting through their ceramite. Several stumbled, their pace slowing as their enhanced physiques struggled against the irradiated metals. The Assault Marines bounded again.

The Dark Angels split their fire.

Plasma tore into the Dreadnought’s chassis, ripping sea-green boulders free. The air flashed sky-blue and tasted of charred ozone. The Contemptor dragged one leg forward in a grinding limp. Bolts ripped from its assault cannon, eviscerating two Interemptors. A stray burst struck Mathias’ plasma incinerator coils. Karael’s brother vanished in a ball of blue-white plasma like a miniature sun. Karael reloaded and gunned down two more traitors. His weapon was unable to harm the Dreadnought, but not its brothers.

Bolts tore an Assault Marine from the skies, scattering his squad mates like starlings fleeing a hawk. Something punched through Karael’s pauldron. Pain stretched into his chest and shoulder from torn flesh and muscles. He fired on a Son wielding a bulky autocannon, the detonations splintering the traitor’s pauldron and breastplate. Blood wept from the cracks. The autocannon chugged to life, reducing an Interemptor to charred scraps. Karael loosed a second burst, ripping out the warrior’s eyes and cheek. The Son howled, wet flaps hanging from his face, his eye a gelatinous ruin. Karael’s iron sights stilled on his throat.

A sea-green comet barrelled into him.

Karael rolled over, pushing himself back to his feet. He ducked under an Assault Marine’s wild decapitating strike, cutting him apart with point-blank bolter fire. A second Assault Marine lunged at him, slicing towards his chest. Karael avoided it, ducking and whirling to stay clear of the gnashing teeth as strike melded with strike. He had no clean shot, nor could he draw his chainblade. His bolter ammunition was low, the last magazine almost dry.

The Son was on him, slicing at his neck. Karael blocked with his forearm. Chain-teeth bit through his gauntlet, shearing away flesh and muscle. Karael snarled and headbutted the traitor. The Assault Marine lurched forward, blood streaming from his broken nose, Horus’ name on his lips. Karael shot him in the face.

The Sons of Horus breached the forward line.

‘Withdraw!’ Derwyn bellowed. Lubricant leaked down his shoulder. His breastplate was ceramite shards and sparking fibre-bundles, blood sizzling on his sword’s disruptor field. It drew a smoking arc across an Assault Marine’s chest. ‘Back to the second line.’

Karael dropped his bolter and snatched a bolt pistol from the fallen Assault Marine. He drew his chainblade and fired the pistol in controlled bursts. Entrails spilled from a Son’s ruptured stomach. Explosive shots vaporised his skull.

Tanis was beside him, firing his plasma burner. It cored a Reaver and two more Sons. The Interemptor was limping, wheezing, his ruined chest sheeting crimson. An Assault Marine vanished in a cloud of ionised particles. Tanis’ signum-rune disappeared, his body shredded by the assault cannon. Three more life-runes faded from Karael’s display, cut down by his mistake as much as the war machine.

‘Wyrmfyre!’ Annael shouted.

Karael recognised the Calibanite battle-cant and quickened his pace, wrestling down the gut-wrenching guilt of leaving his brothers’ bodies behind. Grenades spun over his head. Karael reduced the brightness on his retinal feed to shield his eyes.

Phosphex flared white-green. The crawling, acidic fire splashed the advancing Sons, dissolving armour and devouring living tissue. Traitors collapsed, screaming, immolated inside their battleplate. The smell of roasted flesh lodged in his nostrils.

The Contemptor strode through the fire.

Assault Marines catapulted themselves over it, chainblades angled to strike. They breached the second line before Karael even reached it. He squeezed a burst from his bolt pistol, staggering one and felling another. Through the corner of his eye, he watched Annael and the Naufragia lumber into contact with the Contemptor. Karael could do nothing, fighting with every ounce of strength and discipline to reach the ­embattled second line.

That was their keep.

His chainsword was a snarling blur chased by arterial spray. It bit through flesh and ceramite. Its teeth whickered away in defensive strikes, defanging enemy chainblades as often as itself. Karael thrust and parried, lunged and feinted, employing every iota of skill learned under the Aldurukh drillmasters. The dead formed the Dark Angels’ rampart.

Karael decapitated a legionary in mismatched sea-green and sunburst-yellow battleplate. He deflected clumsy strikes from a Son wracked by facial tics, disembowelling him. They were half-legionaries, hothoused over a period of months and trained in hypnomatic rigs. He slew another with a counter-riposte that punched through his back-mounted power plant.

The Dark Angels’ circle shrank inwards. Karael fought his way to Derwyn’s side, dismembering three more newborns. He thrust for a Son’s stomach, the blow easily turned aside by the warrior’s two-handed power axe. Teeth whickered free and the Son took a step back to face both Dark Angels. His armour was festooned with tribal fetishes and totems, helms from the sons of three Legions clanking against his thighs.

Karael shot an overeager newborn through the throat, swaying aside to avoid the dying warrior. Two more died. He turned, barely in time to parry a wide, curving swing aimed at his throat. Karael counter-attacked, slicing for the traitor’s throat and arms. The Son parried with axe-blade and haft, seeking to overbalance him or lull him into false security. Karael smiled at such an amateur tactic, relishing the prospect of dispatching another foe. A block melded into a sudden overhead swing that caught him completely off guard. Karael cursed and parried, but not well enough. The axe-blade bit deep into his thigh-meat. Pain screamed along his nerves as the blade was wrenched free.

Red sheeted his armour.

Pain-nullifiers flooded Karael’s system, the second’s distraction enough for a lightning strike to his faceplate, fracturing it and breaking the bone underneath. He collapsed, tasting blood. The Son towered over him, axe raised. Karael blocked a downward strike. The second split his chainsword. He met the red eye-lenses, determined to show no fear.

Derwyn was there.

The Praefectus drove the Son back with a devastating series of strikes. He fought like the Lion himself, another Interemptor at his side. The Praefectus’ warplate was matted with gore, much of it his own. His bladework was masterful, every cut, block and thrust timed to perfection. Karael pushed himself to his feet; the unpleasant sensation of bones reknitting set his face itching. He fired into the traitors, spots still blurring his vision.

The Praefectus fell, cut almost in two.

The other Interemptor dragged him back, a salvaged power weapon deflecting the Son’s vicious counter-attack. Bolts punched into the Interemptor. Karael lent his fire to Annael and the surviving Naufragia, cutting down a handful of Sons with converging bolter and plasma fire. The traitors charged the surviving Dark Angels, jeering and firing their bolters from the hip. The axe-wielding Son advanced with grim relish.

Spotlights illuminated them.

A Stormbird’s gimbal-turrets ripped the advancing Sons apart. It hovered on pinions of plasmic fire, spinning on its axis to bring its weapons to bear. Hatches slid open and Dark Angels unloaded their bolters on full-automatic into the traitors, scything them down.

‘Everyone aboard!’ Annael roared. His eyes bored into Karael. ‘Including you.’

Karael hobbled over to the Stormbird, the crevice in his leg making him last to the landing site. A brother hauled him into the gunship. The turbines screamed and the airframe groaned, the pilot pushing into a near-vertical climb to escape the blast radius. Karael lowered himself into a restraint throne, taking in his surviving brothers.

Annael’s skull was torn open and one arm ended at the elbow. Derwyn was a mess of ruptured organs and augmetics. The two Naufragia were broken reflections of their former invincibility and the last Inter­emptor vomited blood beside Derwyn. Tanis was gone. So was Mathias. His squad brothers were dead, along with too many others. A piercing feedback whine drew his attention to the bulkhead-mounted vid-screen.

A lightning-wreathed sphere of wretched light expanded greasily along the skin of reality. It glutted itself on flesh, bone, blood and ceramite. Buildings were torn down and pulled into the vortex, its whetstone shriek piercing in his ears. The smudged suggestions of leering maws and raking claws pressed against the migrainous miasma like water on plastek. It collapsed moments later, a perfect half-sphere carved into the bedrock.

Karael severed his vox-link as the gunship continued its climb. There was no word of the Imperial Fists, nor confirmation his warning had been received.

Karael hung his head and said nothing.