Agent Dorian Fox lives within the shadows of existence and cares for nothing but pleasure, his family, and his secrets. As the fourth Horseman of the Apocalypse, he guards his father's failsafe-a key that will unlock a foe capable of destroying the remaining quarter of the world and those creatures inhabiting it. All that stands between Heaven and Hell on Earth is Death, but the Keeper of Keys holds a deadlier secret. Cain Westcott, a descendant of Lucifer and former slave, searches for his sisters. Separated for years, he refuses to give up hope on saving them from a life of sexual servitude. With two trackers presumed dead, Cain turns to the Arcadian Bureau of Demonic Affairs and there he finds an unexpected ally. However much he cares for Dorian, Cain weaves a web of lies to protect himself from the truth that broke him. By chance, Cain and Dorian are reunited, and their combustion-fueled lust explodes below a mask of mysteries and treachery. When Cain's secrets unravel, he discovers that gritty determination may be the only glue holding his relationship, and the world, together as another veil of truth falls.