Corax must lead the surviving Raven Guard against the Mechanicum-held forge world of Constanix II, if they are to disrupt the traitors' supply of terrifying new war machines.

It's packed with mutated Space Marines, untrusting allies, and the Imperium's first encounter with the unholy daemon machines of the Dark Mechanicum. In this story, Primarch Corax must come to terms with his choices as his past comes back to haunt him - assuming he doesn't get blown up, stabbed or turned inside out along the way...