"Pas si bête" is a comedy about social differences and appearances. Léon Ménard (Bourvil), a farmer and an apparently simple man of the country, is invited to visit his uncle Henri Ménard (Albert Duvaleix), a prosperous industrialist. He encounters a number of people scheming to marry into the Ménard family for the sake of money. Ménard discovers and thwart the plots and manages to unite a young couple who truly are in love. The romantic comedy ends happily with a double marriage. Henri's daughter Nicole (Suzy Carrier) marries Didier (Bernard Lancret), and Ménard marries his new-found love Rosine (Jacqueline Beyrot). It turns out that Léon is "not so stupid" after all.