When an elderly Don apparently commits suicide, Inspector Morse is called in and finds that he has a deep personal involvement in the case. The wife of the dead man, Henry Fallon, is Susan, the woman to whom Morse was engaged to be married many years ago. The inquest confirms the suicide verdict and Morse is about to close the case, when a Dr. John Marriat returns from holiday with startling new evidence. A simple suicide turns into a murder investigation with only one man seemingly capable of having committed the crime. Morse makes no secret of his love for Susan and Sergeant Lewis is becoming increasingly concerned that their relationship is clouding the Chief Inspector's judgement.