Story is primarily based on the adventures of Antoine, a young telegraph messenger on his second night of work. He is given three telegrams, one of which is for the president of the Camber of Deputies. Excited, Antoine runs his bicycle into a truck and loses the telegrams. What follows is an amusing and agonizing search for the missing messages. He is assisted first by a glum, wise-beyond-her-years little girl, Amelie; an off-duty police superintendent, a schoolmaster, a cookie-tin maker and a fireman. The harmonica musical theme is played by Flore Falvey.

In 1919, Pierre Darmont, a handsome, much-loved piano virtuoso, falls in love with Anne Morris, a young woman who shares his tender feelings. But, quite inexplicably, after an unforgettable night, Anne vanishes without trace. Twenty years later, Pierre, at the peak of his glory, has become embittered. Unable to recover his unhappy love affair, he has collected women without ever committing himself to any. Until some night he meets the eyes of a beautiful young lady, who happens to be the spitting image of his great love...

1938, France, Paris, at the Superior Conservatory of Dramatic Art ("Conservatoire Supérieur d'Art Dramatique"). The first-year entrance exams are in full swing. Many applicants, few accepted. Isabelle (Janine Darcey) is one of the few chosen. She joins former students from the second and third years, including François (Claude Dauphin) and Cécilia (Odette Joyeux). They attend the drama class run by Professor Lambertin (Louis Jouvet). The young people, passionate and eager to become comedians, clash in tumultuous love affairs, because by dint of acting, they imagine that life is a farce. François, for example, is in love with Isabelle, who also loves him, but is pursued by Cecilia, his former mistress... "Put art in your life and life in your art!"