John Barratt (Alec Guinness), a lonely, discontented teacher of French language at a British university, vacations in France. There, by chance, he meets his double, French nobleman Jacques De Gué (Guinness again). They become acquainted. Barratt becomes drunk and accepts De Gué's invitation to share his hotel room. When he wakes up the next morning, Barratt finds himself alone in the room, with his clothes and passport missing. De Gué's chauffeur Gaston (Geoffrey Keen) shows up to take his master home, and Barratt is unable to convince him that he is not the nobleman. Gaston calls Dr. Aloin (Noel Howlett), who diagnoses the Englishman as suffering from schizophrenia.