Despite the destruction of Corax's plans to rebuild his legion after the Massacre in the landing zone, the survivors of the Crow Guards remain unbroken. When they stumble upon a wrecked ship carrying the Word far behind the front line, they discover evidence of a new alliance between the traitors and the world-forged Constantiks-2, as well as learn about the new terrifying machines of war marching across the battlefields of the entire sector. The threat is too great to ignore. Primarch Corax must penetrate into the very heart of the priesthood of the Mechanics of Constanix if he wants to find allies for the coming war, although he will probably have to face the truth about his own mysterious nature.