Turnet rose and fired wildly as he ran for the door, both shots smacking into the bridge wall behind Cassar.

'I won't let you do this!' yelled Cassar, returning fire. His first shot went wide, but now Princeps Turnet was struggling with the wheel lock of the door. Cassar lined up his shot on Turnet's back. Titus! Don't do it!' shouted Aruken, wrenching the Titan's primary motor controls around. The Titan lurched madly, the whole bridge tipping like the deck of a ship in a storm. Cassar was thrown back against the wall, the opportunity to take his shot gone. Turnet hauled the door open, throwing

himself from the Titan's bridge and out of Cassar's firing line.

Cassar scrambled to his feet again as the Titan rocked upright. A shape moved in front of him and he almost fired before realising it was Jonah Aruken.

'Titus, come on,' said Aruken. 'Don't do this.'

'I don't have a choice. This is treachery.'

'You don't have to die.'

Cassar jerked his head towards the Titan's eye, through which they could still see the Death Guard moving through the death-slicked trenches. 'Neither do they. You know I am right, Aruken. You know the Warmaster has betrayed the Imperium. If we have the Dies Irae then we can do something about it.'

Aruken looked from Cassar's face to the gun in his hand. 'It's over, Cassar. Just... just give this up.'

'With me or against me, Jonah,’ said Cassar lev-elly. 'The Emperor's faithful or His enemy? Your choice.'

IT HAD OFTEN been said that a Space Marine knew no fear.

Such a statement was not literally true, a Space Marine could know fear, but he had the training and discipline to deal with it and not let it affect him in battle. Captain Saul Tarvitz was no exception, he had faced storms of gunfire and monstrous aliens and even glimpsed the insane predators of the warp, but when Angron charged, he ran.

The primarch smashed through the ruins like a juggernaut. He bellowed insanely and with one sweep of his chainaxe carved two loyal World Eaters in two, bringing his off-hand axe down to bite through the torso of a third. His traitor World Eaters dived over the rubble, blasting with pistols or stabbing with chainblades.

'Die!' bellowed Captain Ehrlen as the loyalists counter-charged, throwing themselves into the enemy as one. Tarvitz was used to Astartes who fought in feints and counter-charges, overlapping fields of fire, picking the enemy apart or sweeping through his ranks with grace and precision. The World Eaters did not fight with the perfection of the Emperor's Children. They fought with anger and hatred, with brutality and the lust for destruction.

And they fought with more hatred than ever before against their own, against the battle-brothers they had warred alongside for years.

Tarvitz scrambled back from the carnage. World Eaters shouldered past him as they charged at Angron, but the butchered bodies lying around showed what fate awaited them. Tarvitz put his shoulder down and hammered through a ruined wall, sprawling into a courtyard where statues stood scarred and beheaded by the day's earlier battles.

He glanced behind him. Thousands of World Eaters were locked in a terrible hurricane of carnage, scrambling to get at one another. At the centre of the bloody hurricane was Angron, massive and terrible as he laid about him with his axes.

Captain Ehrlen crashed down a short distance from him and the World Eater's eyes flickered over Tarvitz before he rolled onto his back and pulled himself to his feet. Ehrlen's face was torn open, a red mask of blood with his eyes the only recognisable feature. A pack of World Eaters descended on him, piling him to the ground and working at him as though they were carving up a side of meat.

Volleys of bolter shots thudded through the walls and the battle spilled into the courtyard, World Eaters wrestling with one another and forcing bolters up to fire point blank or disembowelling their battle-brothers with chainaxes. Tarvitz kicked himself to his feet and ran as a wall collapsed and a dozen traitors surged forward.

He threw himself behind a pillar, bolt shells blasting chunks of marble from it in concussive impacts. The sound of battle followed him and Tarvitz knew that he had to try' and find the Emperor's Children. Only with his fellow warriors alongside him could he impose some form of order on this chaotic fight.

Tarvitz ran, realising that gunfire was directed at him from all angles. He charged through the ruins of a grand dining hall and into a cavernous stonewalled kitchen,

He kept running and smashed his way through the ruins until he found himself in the streets of the Choral City. A burning gunship streaked overhead and crashed into a building in an orange plume of

flame as gunfire stuttered throughout the ruins he had just vacated and Angron's roaring cut through the din of battle.

The magnificent dome of the Precentor's Palace rose above the battle unfolding across the blackened remains of the city.

As Tarvitz made his way through the carnage towards his beloved Emperor's Children, he promised that if he was to meet his death on this blasted world, then he would meet it amongst his battle-brothers, and in death defy the hatred the Warmaster had sown amongst them.

LOKEN WATCHED THE Sons of Horus landing on the far side of the Sirenhold. His Space Marines - he couldn't think of them as 'Sons of Horus' any more - were arrayed around the closest tomb-spire in a formidable defensive formation.

His heavy weapons commanded the valley of shrines through which attackers would have to advance and the Tactical Marines held hard points of rains where they would fight on their own terms.

But the enemy was not the Isstvanian army, they were his brothers.

'I thought they'd bomb us,’ said Torgaddon.

They should have done,’ replied Loken. 'Something went wrong,’

'It'll be Abaddon' said Torgaddon. 'He must have been itching for a chance to take us on face-to-face Horus couldn't have held him back,’

'Or Sedirae,’ echoed Loken, distaste in his voice. The afternoon sun hung in veils between the shadows cast by the walls and the tomb-spires.

'I never thought it would end like this, Tarik,’ said Loken. 'Maybe storming some alien citadel or defending... defending Terra, like something from the epic poems, something romantic, something the remembrancers could get their teeth into. I never thought it could end defending a hole like this against my own battle-brothers,’

'Yes, but then you always were an idealist.'

The Sons of Horns were coming down on the far side of the tomb-spire across the valley, the optimal point to strike from, and Loken knew that this would be the hardest battle he would ever have to fight.

'We don't have to die here,’ said Torgaddon.

Loken looked at him. 'I know, we can win. We can throw everything we have at them. I'll lead them in from the front and then there's a chance that-'

'No,' said Torgaddon. 'I mean we don't have to hold them here. We know we can get through the main gates into the city. If we strike for the Precentor's Palace we could link up with the Emperor's Children or the World Eaters. Lucius said the warning came from Saul Tarvitz so they know we are betrayed.'

'Saul Tarvitz is on Isstvan III?' asked Loken, sudden hope flaring in his heart.

'Apparently so,’ nodded Torgaddon. 'We could help them. Fortify the palace,’

Loken looked back across at the tangle of shrines and tomb-spires. 'You would retreat?'

'I would when there's no chance of victory and we can fight on better terms elsewhere,’

'We'll never have another chance to face them on our own terms, Tarik. The Choral City is gone, this whole damn planet is dead. It's about punishing them for their betrayal and the brothers we have lost,’

We all lost brothers here, Garvi, but dying needlessly won't bring them back. I will have my vengeance, too, but I'm not throwing away the few warriors I have left in a knee jerk act of defiance. Think about this, Loken. Really think, about why you want to fight them here,’