Violette Castillon, a young Parisian lawyer, goes to the Île de Ré where a criminal named Stany claims her to ensure his defense. In exchange, he will tell her the truth about his father, the robber José Rocca, who died several years ago. The day after Violette's arrival on the island, Stany is attacked, a notable from the region is found hanged and other misfortunes befall the island. While the dead are multiplying around her, Violette is determined to discover the truth.