The accident that felled London police detective William Monk has left him with only half a life, because his memory has vanished. The case he is given on his return to the force is a sensatinoal one: the brutal murder of Major the Honourable Joscelin Grey, a Crimean war hero. Monk finds he cannot distinguish friend from foe, and he must grasp desperately for any clue to his own past and to identity of the killer. Each revelation leads him step by terrifying step to the answers he seeks but dreads to find.