Grace Kelly is a woman torn between the loyalty to her husband (Ray Milland) and her new love (Robert Cummings).

When Milland catches wind of her affair he decides to blackmail an old acquaintance into killing his wife. The plans goes awry but Milland seizes the moment to frame his wife for the murder of the would-be assassin.

Milland believes he has created the perfect scheme until a skeptical Scotland Yard inspector begins to investigate.

Filmed and originally briefly released in 3-D, a conventional 2-D format quickly replaced it. The 3-D print was reissued in 1980.

Dial M was the "unofficial" beginning of the Hitchcock "blonde films."

To symbolize the shifting tone of the film, Hitchcock had Kelly dress in bright colors at the onset of the film but made them darker as the film progressed.

Hitch's cameo is in the class reunion photo.