The Tanith First have been pulled back from the front line and are enjoying some well-deserved rest. But that is about to end. An enemy prisoner - one of the deadly Blood Pact - wants to betray his masters, but he will only talk to Colonel-Commissar Ibram Gaunt. Can he be trusted, and what exactly does he know? Gaunt must discover the truth and avert a deadly threat to both his own life and to the Sabbat Worlds Crusade itself.