Newly demoted after stepping out of line once too often, and struggling to adjust, Detective Inspector Tom Thorne becomes convinced that a spate of suicides among the elderly in London is something more sinister. His concerns are dismissed by the murder squad he was once part of and he is forced to investigate alone. Now, unable to trust anybody, Thorne risks losing those closest to him as well as endangering those being targeted by a killer unlike any he has hunted before: a man with nothing to lose and a growing list of victims, a man who appears to have the power to make people take their own lives.
