In postwar Vienna, Austria, Holly Martins, a writer of pulp Westerns, arrives penniless as a guest of his childhood chum Harry Lime, only to learn he has died. Martins develops a conspiracy theory after learning of a "third man" present at the time of Harry's death, running into interference from British officer Major Calloway, and falling head-over-heels for Harry's grief-stricken lover, Anna.
Londoner Harry Fabian is a second-rate con man looking for an angle. After years of putting up with Harry's schemes, his girlfriend, Mary, becomes fed up when he taps her for yet another loan.
Phillipe, the son of an ambassador in London, idolizes Baines, his father's butler, a kind of hero in the eyes of the child, whose perception changes when he accidentally discovers the secret that Baines keeps and witnesses the consequences that adults' lies can cause.
