Manhattan advertising executive Roger Thornhill is already having a hectic day with a jammed packed schedule for its remainder. That schedule takes a turn when he is detained during a business lunch by two men he doesn't know who proceed to kidnap him. Unsure why anyone would want to kidnap him, he discovers the man behind the kidnapping, a Lester Townsend, believes him to be someone named George Kaplan. Townsend wants information from Kaplan, but is prepared to kill Kaplan with or without that information, Kaplan's death meant to look like an accident or suicide. Thornhill is eventually able to escape from his captors. While he does connect with the authorities who do not believe his story, Thornhill subsequently has to go on the run as he becomes implicated in a murder connected to he being Kaplan. As such, Thornhill has to find out what's going on on his own with whatever information he has on hand, most of it gleaned during his captivity: he being able to identify Townsend, his wife, their housekeeper, and three of the thugs working for Townsend; the address of Townsend's mansion where he was being held captive; and Kaplan's recent whereabouts and future movements in what seems to be some tour of the United States, those next two locations being Chicago, Illinois and Rapid City, South Dakota. In his travels in evading both Townsend's people and the authorities, Thornhill gets some willing assistance from a beautiful young blonde woman he meets, industrial designer Eve Kendall, whose help is despite she knowing who he is from the newspaper reports of him being wanted for murder. They eventually fall for each other. She, however, may have some undisclosed ulterior motive for helping him. All the while, Kaplan's people have been and are continuing to watch the proceedings from the sidelines, what they deciding to do largely to protect "Kaplan" from being discovered by "Townsend".