Antoine, a young orphan who lives by the philosophy that "laziness is the mother of all virtue," spends his days with his grandfather in comfort and ease. While they are fishing one day, Antoine falls asleep. In a dream, when his grandfather dies penniless, Antoine sets out equipped only with his charm and carefree philosophy. After making friends with Balthazar, an ice cream vendor, he moves in with the vendor's girl friend, Nicole; when Nicole's affection for him becomes serious, however, Antoine sets off again. This time he ingratiates himself with an eccentric prince who is fascinated by model trains; he moves into the prince's mansion and becomes intimate with Louisette, a housemaid. Soon the impetuous Antoine leaves again, ending up in Rome in a pizzeria where he takes up with the proprietor's buxom wife, Maria. Later, he poses as the best friend of a young millionaire killed in an automobile accident, moves into the family's home, and enjoys the generous hospitality of the host and his five daughters; but when he is offered a job, Antoine vanishes. After a brief dalliance with Clara, an attractive widow, he encounters another millionaire, Von Spiel, who persuades him to write a book consisting of 200 blank pages. Antoine then falls hopelessly in love with and marries Isabelle, a simple young woman; he abandons his irresponsible ways and becomes an iron smelter, toiling endlessly in infernal heat. Antoine awakens to find himself on the quiet lake with his grandfather, who commiserates with him on the unfortunate nightmare.