A well-known writer lives with the obsession of a past drama and, unable to write, wanders from bar to bar at night. One night he meets Marie, whose laughter suddenly resonates for him like an echo. Marie, unable to resist this man who confuses her, will be carried away in an adventure of love at first sight.

One morning, in the Luxembourg Gardens, Paul and Charlotte meet. They had dated years before. The past resurfaces.

The series follows the adventures of lighthearted Jean-Paul Moulin, a police Commissaire, and his team as they solve crimes.