Alec Guinness has double trouble in this stylish mystery thriller costarring Bette Davis, based on the novel by Daphne du Maurier (Rebecca). When John Barratt (Guinness) meets Count Jacques De Gu? (Guinness again) while vacationing in the South of France, the lonely university professor can't believe his eyes.the Count is his exact double! But when Barratt awakens after a night of heavy drinking, he finds De Gu? has vanished, leaving the professor in his place. Unable to convince anyone that he's not the Count, Barratt has no choice but to go along with the sham, fooling De Gu?'s friends and family, including his drug-addled mother (Davis) and jittery rich wife (Irene Worth). But it's only when he uncovers the Count's marriage contract that Barratt slowly tumbles onto De Gu?'s scheme: to murder his wife, run off with his mistress (Nicole Maurey) and dispose of his gullible double.