UNTHINKABLE.

Time had slowed to a pinprick point on which it seemed all the gravity in the cosmos was pressing. Loken felt lead-heavy, slow, out of joint, unable to frame a lucid response, or even begin to deal with what he was seeing.

Was this fear? Was he tasting it now, after all? Was this how terror cowed a mortal man?

Sergeant Udon, his helm a deformed ring of bloody ceramite, lay dead at his feet. Beside him sprawled two other battle-brothers, shot point-blank through the hearts, if not dead then fatally damaged.

Before him stood Jubal, the bolter in his hand.

This was madness. This could not be. Astartes had turned upon Astartes. A Luna Wolf had murdered his own kind. Every law of fraternity and honour that Loken understood and trusted had just been torn as easily as a cobweb. The insanity of this crime would echo forever.

'Jubal? What have you done?'

'Not Jubal. Samus. I am Samus. Samus is all around you. Samus is the man beside you.’

Jubal's voice had a catch to it, a dry giggle. Loken knew he was about to fire again. The rest of Udon's squad, quite as aghast as Loken, stumbled forward, but none raised their bolters. Even in the stark light of what Jubal had just done, not one of them could break the sworn code of the Astartes and fire upon one of their own.

Loken knew he certainly couldn't. He threw his bolter aside and leapt at Jubal.

Xavyer Jubal, commander of Hellebore squad and one of the finest file officers in the company, had already begun to fire. Bolt rounds screeched out across the chamber and struck into the hesitating squad. Another helmet exploded in a welter of blood, bone chips and armour fragments, and another battle-brother crashed to the cave floor. Two more were knocked down beside him as bolt rounds detonated against their torso armour.

Loken smashed into Jubal, and staggered him backwards, trying to pin his arms. Jubal thrashed, sudden fury in his limbs.

'Samus!' he yelled. 'It means the end and the death! Samus will gnaw upon your bones!'

They crashed against a rock wall together with numbing force, splintering stone. Jubal would not relinquish his grip on the murder weapon. Loken drove him backwards against the rock, the drizzle of meltwater spraying down across them both.

'Jubal!'

Loken threw a punch that would have decapitated a mortal man. His fist cracked against Jubal's helm and he repeated the action, driving his fist four or five times against the other's face and chest. The ceramite visor chipped. Another punch, his full weight behind it, and Jubal stumbled. Each stroke of Loken's fist resounded like a smith's hammer in the echoing chamber, steel against steel.

As Jubal stumbled, Loken grabbed his bolter and tore it out of his hand. He hurled it away across the deep stone well.

But Jubal was not yet done. He seized Loken and slammed him sideways into the rock wall. Lumps of stone flew out from the jarring impact. Jubal slammed

him again, swinging Loken bodily into the rock, like a man swinging a heavy sack. Pain flared through Loken's head and he tasted blood in his mouth. He tried to pull away, but Jubal was throwing punches that ploughed into Loken's visor and bounced the back of his head off the wall repeatedly.

The other men were upon them, shouting and grappling to separate them.

'Hold him!' Loken yelled. 'Hold him down!'

They were Astartes, as strong as young gods in their power armour, but they could not do as Loken ordered. Jubal lashed out with a free fist and knocked one of them clean off his feet. Two of the remaining three clung to his back like wrestlers, like human cloaks, trying to pull him down, but he hoisted them up and twisted, throwing them off him.

Such strength. Such unthinkable strength that could shrug off Astartes like target dummies in a practice cage.

Jubal turned on the remaining brother, who launched himself forward to tackle the madman.

'Look out!' Jubal screamed with a cackle. 'Samus is here!'

His lancing right hand met the brother head on. Jubal struck with an open hand, fingers extended, and those fingers drove clean in through the battle-brother's gorget as surely as any speartip. Blood squirted out from the man's throat, through the puncture in the armour. Jubal ripped his hand out, and the brother fell to his knees, choking and gurgling, blood pumping in profuse, pulsing surges from his ruptured throat.

Beyond any thought of reason now, Loken hurled himself at Jubal, but the berserker turned and smacked him away with a mighty back-hand slap.

The power of the blow was stupendous, far beyond anything even an Astartes should have been able to wield. The force was so great that the armour of Jubal's

gauntlet fractured, as did the plating of Loken's shoulder, which took the brunt. Loken blacked out for a split-second, then was aware that he was flying. Jubal had struck him so hard that he was sailing across the stone well and out over the abyssal fault.

Loken struck the arching pier of stone steps. He almost bounced off it, but he managed to grab on, his fingers gouging the ancient stone, his feet swinging above the drop. Meltwater poured down in a thin rain across him, making the steps slick and oily with mineral wash. Loken's fingers began to slide. He remembered dangling in a similar fashion over the tower lip in the 'Emperor's' palace, and snarled in frustrated rage.

Fury pulled him up. Fury, and an intense passion that he would not fail the Warmaster. Not in this. Not in the face of this terrible wrong.

He hauled himself upright on to the pier. It was narrow, no wider than a single path where men could not pass if they met. The gulf, black as the outer void, yawned below him. His limbs were shaking with effort.

He saw Jubal. He was charging forward across the cavern to the foot of the steps, drawing his combat blade. The sword glowed as it powered into life.

Loken wrenched out his own sword. Falling meltwater hissed and sparked as it touched the active metal of the short, stabbing blade.

Jubal bounded up the steps to meet him, slashing with his sword. He was raving still, in a voice that was in no way his own any longer. He struck wildly at Loken, who hopped back up the steps, and then began to deflect the strikes with his own weapon. Sparks flashed, and the blades struck one another like the tolling of a discordant bell. Height was not an advantage in this fight, as Loken had to hunch low to maintain his guard.

Combat swords we're not duelling weapons. Short and double-edged, they were made for stabbing, for battlefield onslaught. They had no reach or subtlety. Jubal hacked with his like an axe, forcing Loken to defend. Their blades cut falling water as they scythed, sizzling and billowing steam into the air.

Loken prided himself on maintaining a masterful discipline and practice of all weapons. He regularly clocked six or eight hours at a time in the flagship's practice cages. He expected all of the men in his command to do likewise. Xavyer Jubal, he knew, was foremost a master with daggers and sparring axes, but no slouch with the sword.

Except today. Jubal had discarded all his skill, or had forgotten it in the flush of madness that had engulfed his mind. He attacked Loken like a maniac, in a frenzy of savage cuts and blows. Loken was likewise forced to dispense with much of his skill in an effort to block and parry. Three times, Loken managed to drive Jubal back down the pier a few steps, but always the other man retaliated and forced Loken higher up the arch. Once, Loken had to leap to avoid a low slice, and barely regained his footing as he landed. In the silver downpour, the steps were treacherous, and it was as much a fight to keep balance as to resist Jubal's constant assault.

It ended suddenly, like a jolt. Jubal passed Loken's guard and sunk the full edge of his blade into Loken's left shoulder plate.