To the public, he's a hero: a brutal killer who targets sex offenders. To most of London's police force, he's the suspect in a gruesome, time-consuming case to be avoided. But to Detective Constable Maeve Kerrigan he's a murderer, and catching him is her job. Assigned to the case with the division's unreadable new DI Josh Derwent, young and inexperienced Maeve is determined to prove she has what it takes.