When a young woman is found brutally murdered on a train, the police call on the brilliant but unstable psychologist Dr. Edward 'Fitz' Fitzgerald for help.
Fitz begins receiving letters from a secret admirer while teaching at the University. However when a murder takes place, the police begin to believe that both are connected.
Fitz returns to Manchester with his wife and youngest son after 10 years living in Australia. He is soon drawn into the investigation of a killer with no apparent motive.