When Detective Chief Inspector Frank Shapiro of Castlemere CID loses his right-hand man to a hit-and-run driver he has two major problems. One is his sergeant, who won’t accept it was an accident: Donovan is convinced it was ordered by local crime baron Jack Carney, and he isn’t the kind of policeman to be put off by lack of evidence. The other is that someone has chosen this moment, with CID already stretched, to launch a career as a serial killer.

But Shapiro finds a useful ally in the inspector sent as a temporary replacement - Liz Graham, who worked under him once before and is eager to prove herself as a senior CID officer. She’s intelligent, intuitive, and ambitious; she knows she’ll have to fight for acceptance in the overwhelmingly male-oriented world of criminal investigation and she won’t let an angry young sergeant who resents her very presence stand in her way.

With the body-count rising and no indication that the murderer will be satisfied, Castlemere CID tries desperately to unravel the strands. As Liz delves into the professional and private lives of the victims she finds a link. But the connection is so ordinary, so innocent, that she struggles to make sense of it. Will someone else die before Liz realizes that, in the desperate mind of the killer, innocence is hiding a terrible guilt? And the person whose malevolent shadow has hung over them since this began remains to be faced in a closing act of startling violence.