The events described take place in the 30s of the last century. Residents of the small English town of Ashford are alarmed by the suicide of widow Margaret Sheldon. However, Inspector Michael Riley has doubts about her voluntary death. The circumstances of the woman's death definitely point to murder, but establishing a motive is not so easy. Soon, an accident leads the police to blackmail, and then another mysterious murder occurs in the town. Riley is sure that all these atrocities are somehow connected and the same person is behind them. During the investigation, the inspector manages to get to the secret hidden in the past, which pushed the killer to commit crimes many years later.