‘Granting that,’ Guilliman said, ‘what of it?’ He looked back and forth between the Lion and the Angel, as if eager to be convinced. That surprised Sanguinius. He expected Guilliman to hold fast to the reason. It was clear the Lion had too. He was watching Guilliman closely, as if the Avenging Son, and not the Lion, was the one bearing strange news. Sanguinius heard doubt in Guilliman’s voice, and he thought it was more doubt in himself than in Davin as a target.

‘The Davinites did not travel to Pandorax by accident,’ said the Lion. ‘Their journey was deliberate. The system was their destination. We found evidence of a ritual, and of mass sacrifice. Now the system is inaccessible. The warp storm is one of the most violent I’ve ever seen.’

‘You infer a connection,’ Guilliman said.

The Lion snorted. ‘What is wrong with you, Roboute? I don’t infer it. I declare it. We have seen too much now to embrace the dangerous fiction of a coincidence.’

‘That is so,’ said Guilliman, ‘but nor can we commit our fleets to anything less than a certainty.’

‘There was a Davinite on Signus Prime,’ Sanguinius said.

The other two primarchs fell silent.

There was much he could not tell them about Signus Prime. For the sake of his sons, and the future of his Legion, the trauma of that war must fall to silence. But he would speak about some of the madness now, so both his brothers could see the path forwards as clearly as he did. Sanguinius didn’t need the Lion to convince him. If necessary, he would convince the Lion. ‘There was a Davinite,’ he said again, ‘and the daemonic attack on the entire system was massive. I saw the stars vanish. I saw a planet made over into the symbol of Chaos. The entire system was transformed. I can’t know what Pandorax is undergoing inside that storm, but I can imagine it.’ He took a breath. ‘Horus fell at Davin,’ he said again. ‘This war begins at Davin. Maybe it ends there too.’

Guilliman said nothing. He looked thoughtful, doubtful, still wanting to be convinced, still unable to let go of the dictates of reason.

‘Did you make any headway towards Terra?’ the Lion asked.

Guilliman shook his head.

‘And we were led here,’ said Sanguinius.

‘That is troubling in and of itself,’ said Guilliman. ‘It suggests we are walking into a trap. If the enemy wants us to take this path, we would be mad to do so.’

‘What enemy?’ the Lion asked. ‘I have not encountered any of the traitor forces.’

‘I have,’ said Guilliman. ‘I have prisoners of the Seventeenth Legion, Navigators who were more than happy to offer to guide me here.’ He turned to Sanguinius. ‘And who led you here?’

‘I don’t know.’