Brilliant, passionate and eccentric, clinical psychologist Dr. Tony Hill (Robson Green) has an extraordinary understanding of the criminal mind. It enables him to empathize with both victim and murderer-and even to visualize the crimes.
Tony suspects a serial killer is luring dejected children to their deaths when the bodies of three young boys are found in different places in Bradfield.
Tony becomes convinced that a series of vicious murders are the work of killer William 'Mack the Knife' MacAdam, who has enrolled as a PhD student in Tony's university class following his release from prison.
Carol recalls Tony from a publicity tour for his latest book to help with an investigation into the murder of a woman beaten to death with a steam iron. A series of bizarre murders follow, but Tony is distracted by the unwelcome attentions of a stalker.
Tony is admitted to the hospital for tests after being hit on the head by a suspect, where it's discovered he has a brain tumor.