A body was found in a zodiac adrift between Fort Boyard and the Ile d'Aix. Solène Brach of the DYP was dispatched to the scene. She asks Vincent, the island's mayor, to assist her, but he is reluctant to participate in this investigation. The victim, José Chebec, is a man from Aix who has just been released from prison after 20 years of imprisonment, who has become a guard of the fort. He and his accomplice, Michel, had carried out a jewelry heist twenty years earlier, which had gone wrong: two victims on the mat, for which José was convicted while Michel remained nowhere to be found. Aline, Michel's wife, has never resigned herself to believing that he is dead, raising their son Mathieu alone. Through the criminal investigation, the whole of island life, where silence intersects with the mysteries and secrets of "family", will be turned upside down...