Roger O. Thornhill, a simple advertising expert, is just having a business meeting when two men threaten him with a gun and kidnap him to a country estate. There he is confronted by Philipp Vandamm, who mistakes him for a certain George Kaplan. Thornhill protests his innocence, but then narrowly escapes an assassination attempt. Caught by the police, they don't believe a word he says. But Thornhill is not to be deterred and sets off in search of the real George Kaplan...