It was without a doubt a very desperate plan, but the alternatives were even less appealing. Only the timely warning from the cruiser had allowed the Ultramarines to break away from the immediate vicinity of the strategium. The sudden massed wave attack of the crew that followed would have pinned them down within a few dozen yards of the command bridge, far from any launch bay or even maintenance portal.

The mutants who hurled themselves along the corridors and hauled themselves up the empty conveyor shafts possessed a frantic demeanour. Nem­etus returned to his earlier diagnosis of martyrdom – they were not only prepared to die, they seemed to embrace it. That they likely had lived terrible, maligned lives was coupled with some offer of a far greater reward, an offer of a post-mortem paradise in exchange for their deaths. Release from living misery coupled with eternal indulgence.

With the corridor cleansed of enemies, Nem­etus joined the perimeter, his heavy tread crushing bodies underfoot while he swapped blade for plasma pistol. No longer concerned about the effect of collateral damage, he fired steadily, plasma blasts turning bulkheads into detonations of molten plasteel every bit as deadly as a grenade. Where the enemy came into the open, they were easy targets, turned to ash and body parts. Within a dozen heartbeats, he stopped firing, the warning runes on his pistol’s plasma chamber gleaming amber with use.

Such was the enemy’s zealotry that they were heedless of the concentrated, measured fire of the Ultramarines. Bolt-round after bolt-round unerringly found its mark, heaping corpses in stairwells and doorways so that the mutants clambered over and pushed through their own dead to get at the Emperor’s warriors.

‘Keep firing. Sustained volley,’ Nem­etus told his brothers. ‘Any bolt left unfired is a bolt wasted.’

Admonius led a counter-charge to the left, aided by the Assault Intercessors. A black point to a spear tip of blue, the Judiciar cleaved into the foe with deadly sweeps of his sword. He fought in silence still, but the battle-brothers that followed gave vent to their battle-ardour, defiant of the cries and screeches of the traitors.

‘Heretis mortalis profanum!’

‘Slay the impure!’

‘I am Guilliman’s blade!’

Many of the mutants were unarmed as they appeared, stooping to pick up clubs, blades and guns from the cadavers of their companions, prising them from dead grips or fishing them from pools of cooling blood. No small number simply charged the Space Marines without armaments, a few perhaps thinking their curled horns or bony protuberances might be effective weapons.

They were wrong. Not sharp spine nor fangs were any threat to the ceramite-clad giants. Bolts, blades and fists made short work of the deranged enemy.