The wealthy industrialist Alain de Narbois has disappeared. Michel Dunant, an idle man who passed by and who looks exactly like the deceased, is taken for Alain by a young woman and her servant. He jumps at the chance but quickly realizes that, in this hushed little world, masters and servants play comedy and know very well that he is only a double of Alain. In fact, the industrialist was assassinated.

Michel Dunan est un garçon sans avenir qui est pris un jour pour un riche disparu Alain de Norbois. Les proches de ce dernier jouent la comédie, et sa maîtresse, Marianne, commence à s'attacher à Michel...