Summary of the main events of the plot

New York City: The publicist Roger Thornhill is to meet his mother for an evening at the theatre. As he stands in a phone booth in the Plaza Hotel he is abducted by communist agents who have mistaken him for a so-called George Kaplan, a fictitious American secret agent. Brought into a luxury mansion, he is first questioned by Philip Vandamm and his men, then drugged and almost killed.

He manages to escape and tries to find the owner of the house, Lester Townsend, a United Nations diplomat. He meets the latter in the hall of the UN but Townsend is stabbed while both men are talking. Thornhill escapes and is chased by the police. In order to find out who George Kaplan is, he boards a train to Chicago and meets Eve Kendall, an attractive woman he falls in love with and who helps him to escape the police. She turns out to be Philip Vandamm’s mistress and organises a fictitious meeting between Thornhill and George Kaplan in the Nevada desert, where Thornhill is attacked by a crop-duster plane. He miraculously escapes. He returns to Chicago where he finds out that Eve is Philip Vandamm’s mistress. When a CIA professor reveals that Kaplan does not actually exist, that Eve actually works for the American government in order to catch Vandamm and that her life is therefore at stake, Thornhill accepts to impersonate George Kaplan. Vandamm meets with Kaplan at Mount Rushmore where the CIA party frames Kaplan’s sham murder. Vandamm discovers that Eve has betrayed him and plans to kill her. Thornhill manages to save her and after a terrible pursuit at Mount Rushmore, the police arrest Vandamm. The film ends with Roger Thornhill and Eve Kendall going on a honeymoon trip aboard the train where they first met.