 New York advertising executive Roger Thornhill is kidnapped by a gang of spies led by Philip Vandamm, who believe Thornhill is CIA agent George Kaplan. Thornhill escapes, but must find Kaplan in order to clear himself of a murder it is believed he committed. Following Kaplan to Chicago as a fugitive from justice, Thornhill is helped by beautiful Eve Kendall. In Chicago, she delivers a message to Kaplan that almost costs Thornhill his life when he is chased across a cornfield by a crop-dusting plane.