A sheet of lightning flashed out. Massak blinked away blindness in time to see the primarch ramming the blade of his sword into the beast’s chest. It withered and shrank as Dorn sawed the lightning-wreathed edge upwards. Massak felt a surge of power in the realm beyond. Red spots of blood blistered his sight. The daemon was straightening, growing even as Rogal Dorn cut it. It grabbed the Praetorian’s shoulder, claws burning as they touched gold. It pulled closer, the blade vanishing into its flesh, its other claw rising.

Loken slowed. His skin was prickling, his breath ice in his throat. Nothing stirred in the reactor chambers. Soot lay across the towers of machinery. White teeth grinned from charred heaps of flesh. There was no sign of living crew. The chamber hummed with the outpouring of reactors into conduits to feed the Phalanx’s flight. There should have been a company of warriors barring his path into this chamber, and a swarm of tech-priests and servitors tending the systems. He had seen none, just drifts of ashes. He was not alone, though. It was here. He could feel it now, gliding over his senses.

He blinked. There was light. Distant flickering around a corner, the blue of plasma.

He moved forwards, so that he could look around the cliff of machinery blocking his view.

A figure stood on a gantry that projected out before a pit of brilliant illumination. Beneath it shone a sphere of blue-hot plasma held in buzzing fields. Arcs of power flicked out of the sphere and burrowed down conduits lined with magnetic coils. Loken knew what it was, though not the mysteries of its working. It was a plasma junction, where the raw power of the reactor was pooled and then drawn off into hungering systems. The woman before it was looking down into it, light playing across her face. Blood dripped slowly from her fingers.

‘Who are you?’ he asked, taking a step forwards. A sound like wind whining through rock fissures slid into the silence. He had his sword in one hand, his bolter in the other.

He could feel the cold breath of the madness in his thoughts. He was Cerberus, the hound of the underworld, vengeance and death.

‘Captain Loken,’ said the figure. ‘Do you have a story to tell?’

He did not hear but took another step forwards, finger ready by the trigger, thumb resting on his blade’s power stud.

‘I can see it. I can see it all. There it is, you see, in the falling water…’ she said, raising her hand, and as she traced an arc up in the air, the world changed.