A film producer is found dead on the island of Saint-Marguerite. Police commanders investigate, questioning the director, producer's wife and associate involved in blackmail while uncovering a cold case linked to the victim's project.

The corpse of the producer Christophe Beaumont has been found in the fort of the island of Sainte-Marguerite: the man was hit in the head and was wearing a iron mask.The police commander Laure Castaldi is in charge of the criminal investigation: in the port of Cannes she meets Florian Rivière, the boatman working for the film team and they go to Sainte-Marguerite where Laure meets her sister and policewoman Manon Castaldi and they begin the investigation: Antoine Chevalier, the director of the film speaks about his friend Christophe and also about Jeanne Beaumont: so Laure and Manon pay a visit to Jeanne who spoke about her tense relationship with Antoine Chevalier.Later they discover that Antoine Chevalier and Christophe had a strong talk about the film.Besides Laure and Manon talk about their relationship and also about the fact that Laure has been adopted.Then Laure and Manon know Paul Ferrand, an associate of Christophe who was blackmailing him.But Antoine Chevalier and Paul Ferrand have good alibis.Then Laure and Manon discover the picture of a woman-something in connection with the film "Gerda":they find the house in the countryside and the corpse of a woman who has been strangulated some 20 years ago.—zutterjp48