Holly Martins (Joseph Cotten), a writer of pulp Westerns, arrives in a bombed-out, post-war Vienna at the invitation of his childhood friend Harry Lime (Orson Welles) only to find him dead. Martins develops the ultimate conspiracy theory after learning of a “third man” present at the time of Harry’s death, butting up against interference from British police officer Major Calloway (Trevor Howard), and falling head-over-heels for Harry’s grief-stricken lover Anna (Alida Valli).