Introducing Annie Greco, the first woman to be appointed commissioner in France in 1971. As soon as she arrived at the Lille police station, she had to go to a crime scene. Actor Richard Planck was found dead in his caravan while filming his new feature film. And the main suspect is the young star of the film, Anna Delange, who had a stormy romantic relationship with Richard. Greco recruits as his deputy the worst head of the police station, inspector Max Beretta, who, in order to deal with his problems of violence, is obliged to follow a therapy with a young psychologist, Rose Bellecour, who is a bit crazy.

Two young models are murdered a few days apart. The first clues lead Gréco to the fashion magazine "Femmes" and its sultry photographer, John Devers, who likes very young girls. When a third young model from the magazine is murdered, the divisional commissioner puts Gréco on the sidelines and entrusts the case to a Parisian crime star. Offended to death, Gréco resigns. But she makes it a point of honour to find the murderer before anyone else. She leads the investigation from her hotel room, with her two assistants Max and Rose in a submarine at the police station.

Beretta is forced to take over as touring guitarist for a famous pop duo.