‘To the limits of my sight.’

‘That is not an answer.’

‘It is still the truth.’

The Lion’s eyes narrowed. ‘Will you be clear, or will I have you destroyed?’

‘I am as clear as blindness permits.’

‘My blindness?’

‘No,’ said the puppet. ‘Mine.’

The admission of limitations was new from Tuchulcha. It was disturbing. ‘If you are blind, how do you know our way is blocked?’

‘Because something will stop my sight.’

‘Where?’

‘My blindness is not measured by location. I know it will occur.’

The Lion went around and around with Tuchulcha, growing more and more uneasy as he became convinced the being was not trying to deceive him. He emerged from the chamber hours later, no wiser than when he had entered. He was left with only the certainty of uncertainty, and the knowledge that he was dragging his brothers down a broken path.

The shadow touched the Blood Angels too. It fell on the Angel first, and spread out from him onto his sons. In the privacy of the Sanctorum Angelus, Sanguinius meditated, seeking the way to find meaning in destiny. Instead, he felt Horus strike the fatal blow. He gasped. He fell to his hands and knees. The marble beneath him did not go dark with his blood, yet every wound was real. His brother’s blade sawed through his hearts. His sight greyed with the pain. A massive figure in black flickered before him, and the walls of the Red Tear shivered, on the verge of becoming the foulness of the Vengeful Spirit.

Dark. Black. Night. Everything was darkness, and so was the thing that rose inside him. It was not blood. It was nothing physical. It was not the thirst. It was something else, so black he could not know it, yet it was his. Yet it was him.

He shouted a denial. His voice rang against marble and gold. He curled in on himself, clutching hard, holding back darkness. It strained to be released. His will was stronger, and as the spectral pain faded, so did the dark. His vision stabilised. The Sanctorum became stable again. He stood up, unsure whether he had claimed a victory or suffered another blow.

Across his fleet, the Blood Angels paused in their preparations for war, and blinked at the wave of anguish that rolled over them.

With the coming of dawn, the shadow did not dissipate. It lingered in the hollows of secret thoughts and fears. It was a venomous dust in the corners of every soul on the surface of Thrinos, and in orbit over it. Mortal and Legiones Astartes and primarch, all felt it, and all moved on to confront it. The warriors of three Legions were ready to make war, and they would burn the shadow from their consciousness with the light of their righteous anger.