‘No, captain. We have reached a sealed door. It’s very large. From its markings, I believe there is a fane on the other side.’

‘Lorgar’s wretched sons want to funnel us into their hall of worship,’ said Hierax.

‘They want to bring the destruction of battle into their shrines?’ Aphovos asked.

‘More likely they think to make a sacrifice of us.’

‘Let them try,’ said a slow, grindingly mechanical voice. Antalcidas, the ancient Deredeo-pattern Dreadnought, marched with Gorthia’s squad.

‘I think we will.’ Hierax looked again at the rubble. ‘Gorthia, I want the precise dimensions of the door and its wall.’

‘Do we make for his position?’ said Aphovos.

‘No. Stand by.’ The trap was effective. If there were other routes to the bridge, it would take time to find them, time the Word ­Bearers could use, and the Ultramarines did not have. The traitors knew the Destroyers would have no choice but to enter the fane, where the ambush would be waiting. But if the hall was as big as Hierax suspected it was, there was another option.

Gorthia relayed the data, and Hierax compared it to what he knew of the deck plan of the superstructure. He couldn’t know the length of the hall behind the door, though it was clear it ran parallel to the blocked corridors. More crucially, the fane appeared to be at least three decks in height.

Hierax turned to the starboard wall and punched it, breaking off more marble. ‘Prepare melta bombs,’ he said. ‘We’re going through this wall. Aphovos, we’re moving laterally. Break through the wall to port. Gorthia, take the door on my signal. We’ll make the ambush ours.’

The bombs ate through the wall, turning stone and metal to smoking rivulets. The tunnel glowed with heat, and Hierax had the impression of moving through the flesh of a living thing. The ship’s hull groaned with the rhythm of the Annunciation’s guns and the impacts of the Cavascor’s assault, but the walls here trembled too much like wounded muscle.

The second set of melta bombs broke through to the other side of the wall. ‘Go,’ Hierax voxed Gorthia. ‘Hit them now!’