Léon Ménard, a farmer and an apparently simple man of the country, is invited to visit his uncle Henri Ménard, 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 marries Didier, and Ménard marries his new-found love Rosine. It turns out that Léon is "not so stupid" after all.
Unfortunately the movie Not So Stupid is not yet available on HBO Max.
| Directing | André Berthomieu | Director |
| Writing | Paul Vandenberghe | Dialogue |
| Writing | André Berthomieu | Screenplay |
| Production | Pierre Gérin | Producer |
| Sound | Maurice Thiriet | Original Music Composer |
| Camera | Fred Langenfeld | Director of Photography |
| Camera | Pierre Franchi | Director of Photography |
| Editing | Jeannette Berton | Editor |
| Costume & Make-Up | René Daudin | Makeup Artist |
| Art | Raymond Nègre | Set Decoration |
