The battle for Niades reaches its epic climax as Ancaeus, Kazarion and Orpheo confront the leaders of the Genestealer Cult. Can even the courage of the Sons of Sanguinius hope to overcome the monstrous might of the Patriarch? Even if they can, all will be for naught if Hadreal and Ignis cannot free the Sword of Baal from the orbital dock and stop the flotilla ships from spreading the curse of Niades to other worlds.