Servais Mont, a freelance photographer who works taking compromising photos, gets fascinated by Nadine Chevalier, a tormented low-budget movie actress married to an eccentric film photo collector.
You can now watch That Most Important Thing: Love online on the following streaming providers in the United States.
| Camera | Ricardo Aronovich | Director of Photography |
| Editing | Christiane Lack | Editor |
| Costume & Make-Up | Catherine Leterrier | Costume Design |
| Production | Albina du Boisrouvray | Producer |
| Production | Léo L. Fuchs | Executive Producer |
| Writing | Christopher Frank | Novel |
| Directing | Andrzej Żuławski | Director |
| Art | Jean-Pierre Kohut-Svelko | Production Design |
| Sound | Georges Delerue | Original Music Composer |
| Costume & Make-Up | Didier Lavergne | Makeup Artist |
| Writing | Andrzej Żuławski | Screenplay |
| Sound | Maurice Laumain | Sound Editor |
| Sound | Jean Nény | Sound Mixer |
| Writing | Christopher Frank | Screenplay |
| Production | Georges Casati | Production Manager |
| Sound | Jacques Gérardot | Sound Recordist |
| Directing | Laurent Ferrier | First Assistant Director |
| Costume & Make-Up | Jean-Max Guérin | Hairstylist |
| Crew | Claude Carliez | Stunt Coordinator |
| Directing | Élisabeth Rappeneau | Script Supervisor |
| Costume & Make-Up | Massimo De Rossi | Makeup Artist |
