Morse is taken aback by the apparent suicide of Anne Staveley. Morse knew her well as they were members of the same choir and he was quite attracted to her. On the evening of the choir's public performance, Morse stops by her house to collect her but finds her front door open and no one at home. On his way home after the performance he sees several police vehicles outside her house and it appears Anne has hung herself. When her nosy neighbour is also killed, Morse is convinced that Anne was murdered.

Morse and Lewis investigate the death of Nicholas Quinn, a hard of hearing Oxford examiner who had recently complained to his superior that others in the examination syndicate were selling secrets. Quinn died of cyanide poisoning but Morse is convinced that this is a case of murder, not suicide. When a second prominent member of the syndicate is killed, Morse looks to the other members for the murderer. What he finds is a maze of deceit and office adultery.

Morse and Lewis investigate the murder of Harry Josephs, a warden at St. Oswald's church who is found dead immediately after a church service. The initial focus is on a tramp who attended the service but the autopsy reveals that Josephs died of an overdose of morphine. When others who attended the same service are killed - including the vicar Lionel Pawlin, the church organist Paul Morris, his 12 year old son and Harry Josephs' wife Brenda - Morse suspect that everyone who attended that particular service is in danger. However, the solution to the case revolves around deceit and mistaken identity.