Detective Inspector Carol Jordan seeks out Dr. Tony Hill, a clinical psychologist, to help police track down the brutal killer in the Northern town of Bradfield. Carol hopes his skill as a profiler will crack the case, but Tony's off-beat methods cause others to dismiss him. Gruesome murders with an apparent sexual bent strike fear into a community, fear grips a city, and no one feels safe.

Tony Hill is brought onto a case by Assistant Chief Commissioner Brandon: the body of a young girl has been found in a Northumberland barn, but the police have nothing to go on. When remains of another girl are found in the same place, Clinical Psychologist Dr Tony Hill immediately suspects a multiple killer.

The brutal killings of a middle-aged grandmother and a young girl bear the shocking hallmarks of the murder of 11-year-old Trudy Hibbert three years earlier. Dr Tony Hill is not convinced that the original suspect is responsible, and the team must face the possibility there may be many more victims before the murderer is found.

Dr Tony Hill is asked to help the police catch the ruthless killer of three men in Bradfield. DI Carol Jordan hopes his profiling expertise will solve the case, but Tony's unconventional methods cause others to dismiss him. When a cop is killed, the pressure for results mounts. The police focus on the gay scene, while Tony is convinced the killer is sending a message on the body of his victim.

A body is found in a remote mountain lake, and Carol calls Tony Hill in to investigate. However, before she can get to grips with the case, she is reassigned to stop a stalker. As both cases take a turn for the worse, Tony and Carol find that they need each other more than ever.

Tony and Carol start working on a paedophile case that proves to be taxing on them. They come across further complications when Carol's boyfriend interferes in the case.