‘We will repel them,’ said Prayto. ‘Our numbers far exceed those the enemy could possibly have inserted.’

‘Then why make the attempt?’

‘Lord Guilliman,’ Altuzer voxed. ‘The enemy has ceased bombardment of the Samothrace.’

‘And the Cavascor?’ Guilliman asked.

‘Still under attack.’

‘Tell Iasus to take the offensive,’ he said. ‘Close with the nearest enemy ship. Use it as a shield and launch assault rams. Turn Captain Hierax and his Destroyers loose on its bridge.’

As he reached the ruined bulkhead, Guilliman paused. ‘Theoretical,’ he said to his warriors. ‘This is more than a simple boarding attack.’ He looked at Prayto. ‘Are you sensing anything?’

Prayto was frowning. ‘Not a build-up, exactly. Nothing in our vicinity to suggest they’re planning a…’ He grimaced. ‘A sorcerous assault.’ The word still did not come easily to anyone in the Legion, even the psykers. ‘But there is something. A presence, I think. Not far.’

‘Then we’re forewarned,’ Guilliman said. He kicked at the buckled door, knocking it out of its frame. He advanced into the corridor more cautiously. Shattered ferrocrete cladding littered the deck. Another splinter had broken through fifty yards down, but there did not appear to be any Word Bearers nearby. Guilliman glared at the shard as he moved past it. It protruded through the hull of the Samothrace as a thing of jagged diagonals and broken lines. Its shape was crystalline. He shared a look with Prayto.

‘This result was not achieved by technological means,’ the Librarian said.

‘But this isn’t the source of what you’re detecting.’

‘No.’

The wind’s keen was high and savage. The twitching light of the Ruinstorm leaked through the fissures between the splinter and the broken hull.

Past the shard, the corridor curved as it approached the port corner of the superstructure. From the bend onwards, the lumen globes in the ornate bronze wall sconces had been smashed. Here, the shadows had breached the Samothrace. They waited for Guilliman. He knew it, and was ready. He raised the Arbitrator. He held the ­Gladius Incandor low at his side, blade angled outwards.

‘It’s close,’ Prayto said.

‘Is it… human?’ Guilliman asked. His reason still rebelled against the word daemon.

‘I’m not sure. It seems grounded in the materium.’

‘But it isn’t a Space Marine.’

Prayto hesitated. ‘I don’t know,’ he admitted. ‘I’m picking up thoughts. It knows you are coming.’

‘That is hardly surprising.’

‘It is eager.’

‘Noted.’ Guilliman was eager too. He anticipated a trap, but he would not deny his anger. The ambush had happened on the edges of Ultramar, but still Ultramar. The boarding of the Samothrace was another insult. He would seek redress in traitor’s blood.

‘Theoretical,’ said Gorod. ‘If the boarding assault has no practical chance of taking the ship, its target must be a narrower one.’

‘Me,’ said Guilliman.

‘Titus’ evidence points in that direction.’

‘I agree. Your practical had better not involve me leading from the rear.’