At the funeral of their best friend Mathieu (40 years old), four boys and three girls meet for the first time. They are between 22 and 26 years old, all knew Mathieu separately, and each of them thought he was his only friend.

One day, on a whim, Marc decides to shave off the moustache he's worn all of his adult life. He waits patiently for his wife's reaction, but neither she nor his friends seem to notice. Stranger still, when he finally tells them, they all insist he never had a moustache. Is Marc going mad? Is he the victim of some elaborate conspiracy? Or has something in the world's order gone terribly awry?

Paris doctor Catherine starts to think her husband, Bernard, is having an affair when she hears an unfamiliar woman's message on his voice mail. Hoping to learn more about his extramarital activities, Catherine heads to a strip club, where she hires call girl Nathalie to have a fling with Gerard. As the affair progresses, Nathalie gives Catherine regular status reports, and the relationship between the women evolves from business to personal.

Unjustly incriminated in a dark case of drug trafficking, Philippe Cazas, a military doctor, had to go into exile in a dispensary in Africa. Five years later, he returns to Paris under military supervision to bury his son who died of an overdose.

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