As DI Nicola Tanner investigates what appears to be a series of organised killings, her partner Susan is brutally murdered, leaving the detective bereft, and vengeful.

Taken off the case, Tanner enlists the help of DI Tom Thorne to pursue a pair of ruthless killers and the broker handing out the deadly contracts. As the killers target their latest victim, Thorne takes the biggest risk of his career and is drawn into a horrifying and disturbing world in which families will do anything to protect their honour.