In 1938, Walter Neff, an experienced salesman of the Pacific All Risk Insurance Co., meets the seductive wife of one of his clients, Phyllis Dietrichson, and they have an affair. Phyllis proposes to kill her husband to receive the proceeds of an accident insurance policy and Walter devises a scheme to receive twice the amount based on a double indemnity clause. When Mr. Dietrichson is found dead on a train-track, the police accept the determination of accidental death. However, the insurance analyst and Walter's best friend Barton Keyes does not buy the story and suspects that Phyllis has murdered her husband with the help of another man.

Four men pull off a daring daytime robbery at a bank, dump the money in a trash can and go their separate ways. Thomas Crown, a successful, wealthy businessman pulls up in his Rolls and collects it. Vickie Anderson, an independent insurance investigator is called in to recover the huge haul. She begins to examine the people who knew enough about the bank to have pulled the robbery and discovers Crown. She begins a tight watch on his every move and begins seeing him socially. How does the planner of the perfect crime react to pressure?