Esther Bazin, a police commander in Nantes, finally captures the killer she had been relentlessly hunting for three years—at the expense of her family life. Despite this success, she resigns that very day to reconnect with her loved ones. However, upon her return, she finds her husband Mathias gone, leaving behind only a note, and the police refuse to investigate; as an adult, Mathias may well have disappeared voluntarily. Distraught, Esther meets Frankie and Douma, volunteers with the GRDV—a group that unofficially investigates voluntary disappearances. Through them, she learns that Mathias was reportedly seen with a woman shortly after vanishing. In exchange for their help, Esther lends her investigative skills to their cases. Together, Esther, Douma, and Frankie form a fragile yet essential alliance, dedicating themselves to finding the people no one else is looking for.

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.