In the elevator of two large Parisian buildings, a telegraph operator discovers the body of an elderly woman, Madame Mathieu, the owner of both buildings. Boucheron (Lucien Baroux), the local superintendent, is dispatched to investigate, along with his rival, Inspector Lambert of the "Sûreté" (Jacques Baumer). To solve the enigma, they scour staircases and corridors, visiting every floor of both buildings, courtyard and facade. Their gruff rivalry allows them to complement each other in discovering who committed the crime among a gallery of characters, humble or rich, who all have something to be ashamed of... A rare, fast-paced, picturesque comedy set against the backdrop of a police mystery.
| Directing | Yves Mirande | Director |
| Directing | Georges Lacombe | Director |
| Writing | Yves Mirande | Writer |
| Writing | Yves Mirande | Dialogue |
| Writing | Georges Lacombe | Co-Writer |
| Writing | Max Kolpé | Co-Writer |
| Camera | Victor Arménise | Camera Operator |
| Camera | Robert Juillard | Camera Operator |
| Camera | Jacques Robin | Assistant Camera |
| Art | Lucien Aguettand | Set Decoration |
| Art | Lucien Aguettand | Decorator |
| Sound | André Gailhard | Original Music Composer |
| Sound | Jean Wiener | Music |
| Directing | Jacques Henri-Robert | Assistant Director |
| Editing | Marthe Poncin | Editor |
| Editing | Marie Le Bars | Assistant Editor |
| Production | Lucien Pinoteau | General Manager |
| Sound | Robert Ivonnet | Sound Engineer |
| Crew | Madeleine Lefèvre | Script |
| Art | Louis Demasure | Set Supervisor |
| Camera | Jean Joffre | Set Photographer |
| Costume & Make-Up | Igor Keldich | Makeup Artist |
| Production | Robert Vernay | Administration |