Marcel Carné's farcical satire on Scotland Yard crime detection features Michel Simon as the head of a bourgeois family, by day an eccentric botanist, by night the writer of crime stories inspired by his daughter, who hears them from her lover, the milkman. Louis Jouvet is the hypocritical vicar who, convinced that detective-story writers are potential murderers, brings Scotland Yard into the scene. Out of the melee emerges William Kramps (Jean Louis Barrault), the comical homicidal killer who loves animals but frightens the botanist out of his wits.