Tony Hill assists the police in investigating a series of murders. His profile suggests that the man committing these crimes may come forward as a potential witness and the police soon focus in on Bernard Kelly. In his mid-30's and still living at home with a domineering mother, he seems to fit his profile, but Tony has nagging doubts as he finds significant differences in style between some of the attacks. During this time Tony has a house guest, his old friend from university Jonathan Good who is also a psychologist. As time goes by however, he begins to behave erratically. DI Alex Fielding is up for promotion to DCI but is having doubts, as it would likely mean having to relocate to a new city.