Tony Wendice has married his wife, Margot, for her money and now plans to murder her for the same reason. He arranges the perfect murder. He blackmails a scoundrel he used to know into strangling her for a fee of 1,000 pounds, and arranges a brilliant alibi for himself. Unfortunately.the murderer gets murdered and the victim survives. But this doesn't baffle the husband: He sees his hireling's death as an opportunity to have his wife convicted for the murder of the man who tried to murder her!