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