Georges, 75, mysteriously disappears from the Pornic waterfront during an organized trip for seniors. The GRDV team questions group members, port regulars, and the trip supervisors—including Jordan, a young man close to Georges. Gradually, they discover that the seemingly kindly old man is actually hiding a murky past that has come back to haunt him. Meanwhile, Esther, Frankie, and Douma follow a lead pointing to Christophe Absi, whom Mathias had apparently been trying to reach through his lawyer. Douma faces struggles in his relationship and with his basketball team, while Frankie meets Boris.

Samuel, a journalist in a high-profile relationship, suddenly disappears following a strange phone call. The GRDV investigates at his wife's request but runs up against a tight-knit, uncooperative circle. Meanwhile, Esther plans to use Absi to infiltrate a private club and make headway in the case of Mathias's disappearance. She also tries to reconnect with her son Théo, while Douma takes Nawaz—a young, homeless player—under his wing. For her part, Frankie questions what role she is willing to let Boris play in her life.