Curze cocked his head at the sound of the klaxons. ‘I hear the blaring of your time running out,’ he said.

‘There is time enough,’ Sanguinius said. He thought of what Curze had done to his sons. He thought of the dead of the Sanguinary Guard on Macragge, and of Azkaellon’s severed arm. He faced his rage at his brother’s crimes. Then he did what was necessary for the Imperium, and for his father. He yanked on the chain attached to Curze’s neck and hauled the Night Haunter into a run down the corridor.

Curze laughed as they ran past the fallen guards. ‘You do your very best to bring me joy, brother.’

‘Sanguinius,’ the Lion shouted through the Angel’s vox-bead. ‘What are you doing?’

‘What I must. As you are. But you are wrong.’

‘You are setting us against each other. This is madness.’

‘No. It is necessary, and it is fated.’ He shut down the channel, cutting the Lion off mid-roar.

Sanguinius opened a vox-channel to his Chapter Masters, grateful for the preparations he had made before taking the Thunderhawk to the Invincible Reason. ‘Launch drop pods,’ he ordered. ‘Immediate landing in the vicinity of the temple. All forces away, now!’

He and Curze ran down the halls of the Dark Angels battleship, racing for the bay where his gunship waited. The Night Haunter kept laughing, and laughed harder as the Lion sent troops to stop them, and Sanguinius battered them down. With every Dark Angel he harmed, Sanguinius felt the knot of destiny closing, growing tighter, choking off one future after another. He did not know how far the Lion would go to stop him. Sanguinius was pushing him hard, risking the fragile trust that existed between the brothers. We only really trust ourselves, he thought. If we can even be said to do that.

‘The Ninth Legion is landing in force,’ Holguin observed.

The Lion gripped the arms of his throne. He took a breath, forcing himself to see clearly through the red haze of anger.

‘Sanguinius must be mad,’ Farith Redloss said.

‘Launch from bay thirty,’ a servitor’s mechanical voice intoned. The flat announcement signalled the flight of the Thunderhawk Vyssini from the Invincible Reason.

‘Auspex,’ the Lion said, ‘give me a trajectory.’

‘Towards Davin, my lord.’

‘What are your orders?’ Stenius asked.

Do we shoot my brother down, you mean? the Lion thought. Wood creaked beneath his grip. Damn you, Sanguinius. Damn you for forcing that choice on me. ‘Track it all the way down,’ he said. He knew where the Angel was heading. He gave the command solely because one was needed.

‘Why did he take Curze?’ said Holguin. ‘What sense does that make?’

‘None,’ said Redloss. ‘Is he mad?’

‘He acts according to his convictions,’ the Lion said. ‘He is wrong. And we must act for the Imperium.’

‘The fleet is in position,’ Stenius said. ‘Bombardment targets locked.’

‘So noted, captain,’ the Lion said.