The galaxy is engulfed in flames. The power of Chaos rises among the stars. The Great Rift split the realms of the Imperium in two, isolating entire sectors from the light of Sacred Terra. But hope is not lost yet. Primarch Roboute Guilliman returned from his immortal slumber and appointed Commander Dante, Lord of the Blood Angels, as regent and Guardian of the territory newly christened Imperium-Nihilus. In the Baal system, the order's devastated holdings are being rebuilt, and Dante plans the greatest campaign of his long life - to recapture half of the empire. But at this moment of rebirth, other dangers lurk very close by, capable of destroying everyone in whose veins the blood of Sanguinius flows, and nipping Dante’s noble endeavors in the bud. The flaw of the sons of Sanguinius is growing stronger. The twin curses of the Red Thirst and the Black Rage threaten all, and the greatest test falls on Mephiston, the twice-born Lord of Death and Chief Librarian of the Blood Angels. Perhaps, among the mighty lords of Bhaal, only he is able to save them all - by mastering the darkness in his blood...