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 one thousand 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, and that is what almost happens. Luckily, the police inspector from Scotland Yard and a young man who is in love with the wife discover the truth, and in a scene of almost unbearable suspense they trap the husband into revealing his guilt, thus freeing Margot.