Gangsters from the United States try to kill a key government witness whose testimony could help land an influential mobster in jail. It's up to detective Maigret to deal with the FBI and a series of underworld figures to save the life of the witness...
| Directing | Gilles Grangier | Director |
| Writing | Georges Simenon | Novel |
| Writing | Gilles Grangier | Adaptation |
| Writing | Jacques Robert | Adaptation |
| Writing | Jacques Robert | Dialogue |
| Camera | Louis Page | Director of Photography |
| Sound | Jean Rieul | Sound Engineer |
| Editing | Marie-Sophie Dubus | Editor |
| Sound | Francis Lemarque | Original Music Composer |
| Sound | Michel Legrand | Original Music Composer |
| Production | Georges Charlot | Production Director |
| Production | Raymond Danon | Producer |
| Art | Jacques Colombier | Art Direction |
| Art | Albert Volper | Set Decoration |
| Costume & Make-Up | Janine Casse | Makeup Artist |
| Costume & Make-Up | Yvonne Gasperina | Makeup Artist |
