Robin, 25, is one of the best divers in the creeks. With his friend Matthieu, he went to the creek of En Vau, in Cassis, famous for its "steep" of more than 20 meters. It's 5 p.m., Robin dives before Mathieu, but doesn't come back up. Or rather, it comes back up after two long minutes, as if rejected by the sea, drowned. The death of such an experienced diver seems suspicious. The Maréchale des Logis chief Emilie Pradot is in charge of the investigation. She begins by questioning Matthew. For him, it's incomprehensible, this place, they know it inside out. Bruno Tourneur, a former military combat swimmer, is the expert sent by the gendarmerie to support Elodie...