'Reject the taint in all its perfidy,' Orad began, spitting vitriol against the inner surface of his skull-mask. 'Resist and crush those who worship Chaos. Know in your hearts you are pure of purpose and that the Emperor walks with you. His light will vanquish the traitor and the daemon.' As the engines thrashed, the sound reverberated and intensified around the hold. Orad fought it, his oratory rising from a shout to a scream. An explosion nearby rocked the Rhino on its tracks, but he kept his feet. 'The Ultramarines fight with clenched fist around bolter and blade. We are the inheritors of Guilliman, the heirs of Ultramar. They know our names and they quail as we recite them with bolters as our voice.'

The engine slowed as the Rhino struck the enemy. A lethal rank of spikes gave the hard nose of the tank a killing edge. Crunching bone, the spatter of blood and the screams of the dead came dully through the hull. A body rolled under the tracks something big and the Rhino lurched up and over it before landing square.

'For the glory of Ultramar, we shall know no fear!'

Screeching to a halt, the tank's hatch slammed open and the Ultramarines charged out with Orad at their head.

Blood and death greeted their arrival. Cultists clad in rags, wrapped in pus-soaked bandages pressed in, a horde of the unwashed. The Chaplain cut through them, his crozius blooded, leaving a string of enemy corpses in his wake.

Scipio was behind him, he had a perfect view of Orad's back. His shoulder plates compensated for the movement allowing his arm to rise and fall like a piston as he bludgeoned. Rancid flesh gummed the brunt of his crozius. He flicked it off with a desultory gesture as a sporadic muzzle flare lit the end of his bolt pistol. Punished heretics exploded as the ma.s.s-reactive sh.e.l.ls did their holy work. He'd engraved every one with a litany of hate and purging. Orad knew their order in the weapon's chamber and spoke each and every one as it killed a traitor. Nothing stayed his wrath.

It was... inspiring inspiring.

Chainsword chugging on the flesh of a dying cultist, Scipio forged himself a little s.p.a.ce and briefly examined the battlefield.

Across the roadway, on the opposite side of the gate, a second squad of Ultramarines had deployed. Like Scipio's Thunderbolts, they were swarmed by enemies. He recognised Sergeant Solinus immediately and felt an urge to breach the gatehouse before him. Given Orad's fervour, the Chaplain wanted that honour too.

'Repel them!' he roared. 'Smite them! Become the Angels of Death!'

He was locked in battle with a ferocious warp-thing, a possessed flesh puppet of some daemon from the abyss. Tentacled appendages spewed from the creature's distended maw. Several fizzed and burned against the Chaplain's rosarius field impelled from the icon chained around his gorget, but at least one got through and bit into his power armour.

Pressed by his own opponents, Scipio thought he heard Orad grunt and saw the protective energy field flicker for but a moment when the Chaplain dispatched the bloated h.e.l.l-beast with a hate-filled curse.

Sensing a shift in momentum, Scipio ordered his warriors with even more aggressive tactics. Bolters were slung in favour of gladius and pistol as the Thunderbolts closed hand-to-hand. Brakkius snapped a cultist in two across his armoured knee, whilst Ortus stabbed another in the throat and crushed the skull of a second in his gauntlet.

Cator unleashed a ragged line of fiery promethium into the decaying ranks from his flamer and they burned. Combined with the furious blade a.s.sault it tore enough of a gap for the Thunderbolts to advance, gaining precious ground into the gatehouse and the inner citadel beyond.

The horde of traitors that had sallied forth was slowly being cut down. Helios kept up a furious but disciplined barrage from the edge of the Ultramarines battle line, withering the enemy troops that had sought to flee the fighting.

Nothing must survive. Those were Calgar's orders.

Ground under the tracks of tanks, eviscerated by blades or crushed underfoot, it didn't matter the only sure way to cleanse the fortress was to systematically eradicate everything inside.

Once the tactical squads were in, the Terminators would begin their implacable march to the gates. The Mordians would follow, bringing tanks and more flamers for the purge.

Elsewhere on the battlefield the Tenth were taking down gun towers, cutting off supply points and collapsing defences under Master Telion's expert direction. Several weapon emplacements had already been sabotaged, leaving behind twisted metal and blast-scarred sandbags.

A plasma cannon turret, protected inside a mobile bunker, slowly turned to draw a bead on the Thunderbolts. Its rotational axle was slicked with pus instead of oil, and the bulbous maw of the weapon that extruded from the firing slit was malformed with corrosion. The weapon had almost built to expulsion when an explosive typhoon engulfed it more of the Scouts' unseen work. Shrapnel and flesh-parts pattered against Scipio's armour as the Ultramarines fought through the last of the cultists and entered the courtyard behind them.

'Glory to the Thunderbolts,' said Scipio quickly but good-naturedly to Solinus.

'It is for the Chapter, Brother-Sergeant Vorola.n.u.s,' Orad said before Solinus could reply.

Both sergeants bowed to the Chaplain's wisdom before moving into a slow run towards the inner citadel, a craggy, gore-stained structure that poked out of the centre of the bastion like a diseased talon.

It was the briefest of respites as they crossed the courtyard, which was littered with the dead but otherwise empty of threat, and reached the portal to the inner citadel. The door was like an open wound, festering with decay. Veins pulsed in the marblesque rock, like arteries swollen with plague. But it was unbarred.

Orad held the others back with his outstretched arm as he stood at the threshold of the inner citadel, staring. 'It is dark as sin, but the way is open to us,' he said. As he led them onwards down a shallow set of steps, Scipio thought he heard Orad's sharp intake of breath. It sounded like pain.

'Brother-Chaplain?'

'It's nothing,' said Orad, though the timbre of his voice suggested he was injured. It had a faint gurgling quality, like there was blood or mucus in his throat.

One of the warp-thing's barbs had got past his rosarius field and penetrated his power armour too. Scipio noticed crusting around the wound and some of the ceramite had even started to corrode.

Scipio paused, uncertain what to do.

'It's nothing,' Orad said more vehemently and just for the sergeant this time. 'Our enemy is close. We must destroy it. I will seek out an Apothecary later.'

He turned, signalling an end to it, and beckoned the Ultramarines on, closer to the nest of evil.

There was a stink upon the air, copper-blood and the reek of putrefaction. Corpse-fattened spiders and bloated flies skittered from the light as the Ultramarines switched on their lamp-packs. Grainy lances of magnesium white stabbed into the blackness in all directions. There were alcoves where more corpses lingered, slumped against columns or strewn over debris from the fallen ceiling. The only route further into the citadel was ahead, over a stinking carpet of mould that stuck to the Ultramarines' boots and led to a temple of horrors.

'Steel yourselves,' hissed Orad as they arrived at the entrance, the oleaginous glow of rancid lanterns spilling sticky light ahead of it.

As he touched the rim of the light, Scipio could almost feel it coating his armour in a film of decay. He suppressed the urge to remove his trappings and be free of the taint, wanting nothing more than to experience the cleansing fury of his ritual ablutions.

The foetid temple was no better.

Rusted chains hung lankly from a pitted ceiling, strung with flayed corpses and gossamer-thin webs of flesh-dust. Filth-streaked columns were inscribed with ruinous sigils and contained alcoves bearing cadaverous, half-fleshed skulls. A pit was hewn in the centre of the room, which had once been some kind of great hall but was now divested of its former use and put towards corruption. Something boiled within it, wallowing in a soup of pestilence. Noxious bubbles belched to the surface as the creature moved, disturbing bleached skulls and half-digested viscera.

So it wasn't only a temple, it was also the abomination's feasting chamber. It was the very root of evil on Karthax.

Orad had seen enough.

'Destroy it!'

Squads Scipio and Solinus unleashed their weapons in a terrifying storm at the loathsome sp.a.w.n in the filth-pool. For a moment, it was utterly obscured from view by the Ultramarines' blistering salvo.

After a full minute of the h.e.l.l-storm, the reports of bolters and the hiss of flamers slowly echoed away around the circular room. Smoke and fire trailed from the pit afterwards. Most of its disgusting contents had been splattered around the walls or flecked the Ultramarines' power armour.

As the smoke cleared, Orad ordered Solinus forwards. The sergeant acknowledged, and approached the edge of the pit warily. He used his boot to nudge something within it, leaning back from the sight suddenly repulsed.

'There is a body,' Solinus waved the others forwards.

Scipio crouched by the ragged corpse of a man. He was wearing robes and his flesh and bones had been utterly sundered. Bolt impacts marked his body. His exploded limbs and innards, the shattered bones and scorched skin were testament to the effectiveness of the Ultramarines' weapons.

'A sanctioned psyker of some sort,' he decided, noting sigil-marks on the skin the fusillade hadn't obliterated. 'Cursed by Nurgle.'

'So where is it?' asked Solinus.

Scipio met his gaze, questioning.

'Where is the beast?' the other sergeant clarified.

'That was not the creature I burned,' offered Cator.

His battle-brothers were right. This thing was a puppet; no more than a vessel for whatever ent.i.ty had claimed this place and transformed it into its own wretched domain. Where was the plaguebearer that had claimed the soul of this man?

Scipio turned around at the sound of ceramite clattering against stone behind them.

'Brother-Chaplain, replace your battle-helm. This place is unclean!'

He went to go to Orad but was held back by the Chaplain's warding hand. The wound in his power armour was seeping gore and pus. It crusted his entire forearm and was spreading.

His words were thick with phlegm. 'Stay back.'

'Lords of Ultramar,' Solinus gasped and reached for his bolt pistol. 'It has taken him, it has taken our Chaplain.'

Scipio pushed down his aim. 'Wait!'

Orad went to speak again but bent double and vomited a stream of corruption. Chin drooling with sick, he spat a last gobbet of the stuff from his mouth. His eyes were sunken in his skull, the old wounds on his face throbbing, raw and reopened. He sank down, knee deep in the filth. His crozius fell from his grasp.

'What are you doing?' snapped Solinus. 'He has the taint we must end him now!' He shook off Scipio's grasp and brought up the weapon again.

Scipio stepped into his line of sight. 'He is our Chaplain. Of us all, his faith is the most devout. How can this be?'

'It matters not. Stand aside, now.'

Ever since Scipio had been a Scout, Orad had been his Chaplain. He had counselled his doubts on Black Reach, had instilled the power of his faith in him. And now he was d.a.m.ned, reduced to no more than a vessel for an insidious terror. The taint of Chaos had claimed him. It had breached his aegis through the smallest of cracks, widened it and rotted him from within.

Scipio drew his own sidearm. His voice was low and solemn. 'I will do it.'

Nodding, Solinus lowered his aim. 'Then do it quickly, before it is too late.'

Orad had wrapped his arms around his torso and was convulsing violently in the pool of filth he had created. There was no sentience in his eyes any more. He was a gibbering wreck, a once proud servant of Ultramar brought low.

But when Scipio drew a bead upon the Chaplain he hesitated.

There must be a way. Orad can repulse it.

In eerie synchronicity with the sergeant's thoughts, the Chaplain's neck snapped up and his dead eyes fixed onto Scipio's pitiless retinal lenses.

'Mercy...'

The trigger squeezed a little tighter in Scipio's grasp, but he couldn't do it. Orad shook with a sudden palsy. Something within the Chaplain was changing.

The sergeant felt a hand on his pauldron. The world was slowing as if mired in the very foul stuff that pervaded the temple. The reek of death and decay overtook the chamber, more noisome than ever.

'Kill it! Do it now!'

Scipio was only dimly aware of Solinus's urgent voice, of the slow chank chank of bolter sh.e.l.ls filling their chambers, of the bounds of Orad's armour bursting apart like an overfilled lung. of bolter sh.e.l.ls filling their chambers, of the bounds of Orad's armour bursting apart like an overfilled lung.

Too late the first sh.e.l.l spat from Scipio's pistol, its burning contrails flashing in the air. The sheer la.s.situde of its trajectory brought on by the h.e.l.l-transformation unfolding before him allowed Scipio to appreciate every spark, every mote of flame.

Too late, other sh.e.l.ls joined it from the battle-brothers around him; nascent spits of flamer too and the glowing coruscation from a plasma gun.

Too late, Scipio realised what his hesitancy had cost them and shouted a warning to Brother Naius.

The husk of Orad's armour broke apart under the barrage but the creature that had stolen the Chaplain's flesh was no longer there. It had leapt onto the ceiling, latching to the rock with the acid-slime on its claws, spewing out barbed tendrils from a distended maw.

Three of the tendrils punched through Naius's chestplate and he fell, bolter loosing off wild rounds as he died and his death grip clenched.

Scipio reached him a fraction too late. He bundled Naius over with the barbs still hooked in him. They stretched and ripped free as he went down, breaking open ceramite and taking chunks of flesh into the darkness above as the beast retracted them. Then it was gone.

'Naius!' Scipio unleashed a burst into the gloom but hit only rockcrete. It was a pointless act, save for the fact of venting his anger. Resting a hand over the neck where Naius's only intact progenoid was still harboured, Scipio got to his feet. He had been one of Solinus's squad and now his legacy had ended all because Scipio had hesitated. The Ultramarines were on the offensive, searching the vaults in the temple above, throwing out random bursts of fire as someone saw a shadow or detected the insidious scuttling of the daemon.

Avoiding Solinus's furious gaze, Scipio went on the hunt for the thing too, determined to avenge Naius. It was Orad no longer. Trapped for a moment in the lurid glare of a pestilential lantern, the Ultramarines saw an abomination where once had been their Chaplain. Gelid-skinned, surrounded by flies, it was more corpse than man. A horn had sprouted from the daemon's head; claws replaced hands; it had hooves instead of feet. It was emaciated, its innards showing through diaphanous skin. Pustules and boils puckered flesh that sagged like melted wax and a grotesque hump bent the monster's back.

Seeing the Ultramarines' obvious disgust, it chuckled.

'What's wrong... brothers brothers?' Its hideous voice was a slurred parody of Orad's.

Bolter impacts riddled the wall where it was clinging like some human spider, but went wide of the mark. For such a diseased beast it was quick, racing up pillars and skittering through the shadows too fast for the s.p.a.ce Marines to bring it down.

'Keep it pinned,' shouted Solinus, directing warriors left and right in pairs. Three battle-brothers guarded the temple entrance and were primed to release a deadly salvo if the creature came within range and sight.

Scipio did the same and was about to give chase, determined the beast that had killed Orad would not escape, when something seized his arm. At first, he thought it might be Solinus and he turned with defiance on his lips. That emotion turned to horror when he realised it was Brother Naius. His armour was corroding from the inside out. A bloodshot eye, rampant with pestilence, glared madly from a wound in his eye socket. The point where the tendrils had pierced his chest bulged, cracking his plastron.

Swinging round his chainsword, Scipio cut Naius down the second son of Ultramar he had condemned by his inaction finishing him with a blast from his pistol.

Or so he thought.

Partially exploded, a huge cavity in his stomach yawning open with pustulant debris, the undead-Naius rose on twisted limbs. The chainsword had chewed off part of his helmet. Blackened nubs of teeth bared in a snarl as the creature came at Scipio.

'Brother!' The sergeant ducked when he recognised Cator's voice. A whoosh whoosh of rapidly expelled promethium followed, sending heat spikes registering on Scipio's retinal display when the flamer burst just missed him. It engulfed the undead-Naius, though, eliciting a scream that was no longer wrenched from his former brother's lips. of rapidly expelled promethium followed, sending heat spikes registering on Scipio's retinal display when the flamer burst just missed him. It engulfed the undead-Naius, though, eliciting a scream that was no longer wrenched from his former brother's lips.

'Don't let the mouth barbs touch you,' Scipio warned, backing up and searching the shadows. Behind him, Naius burned away to ash, leaving rotten armour in his wake.

Seven grotesque pillars supported the vaulted ceiling of the plague temple. The daemon weaved and scuttled between them, using the darkness to thwart the Ultramarines.

'Herd it!' Solinus bellowed, his voice echoing from somewhere deeper in the vast room. Sporadic bolter fire followed and Scipio thought he saw the silhouette of something unholy coming his way. He pressed his body against one of the pillars and waited. He couldn't see the daemon but he could sense it. Not in a psychic way, Scipio was no Librarian. But it was in his nose, despite his olfactory filters; it veneered his skin, though he wore power armour over a mesh bodyglove; it buzzed in his ears like the droning of flies.

Scipio shut his eyes and focussed on his instincts. The creature was fast but not impossibly so. He owed it to Orad, to Naius, to kill it.

Close now. The shouting of his battle-brothers was getting nearer. They were operating in a dispersed formation in order to cover the most ground. He heard Cator and Brakkius, the clipped shots of Ortus in the vicinity.

Not yet. He pressed against the pillar, denying the urge to engage, to wreak b.l.o.o.d.y havoc as an avenging Angel of Death. He needed for it to come closer.

When the moment arrived it almost took him by surprise, but Scipio's body was honed, conditioned to preternatural levels and it reacted out of instinct. He opened his eyes. Springing from cover, his chainsword was already swinging. The mouth tendrils spilled like dead worms as the blade-teeth cut through them. The blade continued its buzzing trajectory, embedding in the rib bone all the way to the base of the sternum. Face-to-face with the daemon, Scipio levelled his bolt pistol and for a split second it was Orad there and not a plaguebearer.

'Brother' it began to mouth, a look of anguish on its diseased face.

'Get back to the abyss!' The bolt pistol fired and the sh.e.l.l struck the daemon in the eye, turning the creature back to its true form. It still wore Orad's flesh, strips of body-mesh clung tenaciously to his enhanced musculature, but it was not him.

It isn't him...

The plaguebearer's visage exploded in a bloom of viscera and bone-chips as the ma.s.s reactive sh.e.l.l detonated, leaving it without a head. It sagged, deflated almost, as a keening wail ripped the air like a fat blade. Ichor exuded from the orifice in the neck, pooling about the dead Chaplain's shoulders. The daemon was banished; its meat puppet was Orad again. A dead and decapitated Orad, but it was him.