The GRDV reopens the case of Antoine—missing for fifteen years—after his mother claims to have seen him again recently. Esther, Frankie, and Douma investigate this unsettling reappearance, navigating doubt, uncertain leads, and buried truths. Meanwhile, Esther edges dangerously close to the truth about Mathias, while Théo pursues a lead on his own—at his own peril. Douma also discovers that Nawaz has gone missing, as Frankie faces a crucial decision regarding Boris. In a high-tension finale, events accelerate rapidly, and long-held certainties are shattered.

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.

Eugène Laborde turns to the GRDV following the disappearance of his granddaughter Manon, who has been missing for five weeks. As an adult, Manon is not being sought by the police, even though she vanished right in the middle of her bachelorette party. While tracing her steps, Esther, Frankie, and Douma find old demons resurfacing—putting Esther under immense strain. Meanwhile, Esther pursues the lead regarding Christophe Absi, convinced that Mathias had serious trouble with him. Tenacious, she is willing to do whatever it takes to make progress, even if it means clashing with her former colleagues and facing Douma's growing concern.

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.

Esther continues the investigation into the disappearance of Mathias with Frankie, a lead leads them to a lawyer that her husband would have consulted under the pretext of divorce. Meanwhile, Douma puts up with the failures of his basketball team and takes a dim view of Esther's arrival in the GRDV world. When Yanis reports the worrying disappearance of her mother, Frankie offers to integrate Esther into the group to strengthen the investigation. Suspicious, Douma nevertheless accepts her help, on the condition that she proves herself within the team. Between the search for Mathias and this new urgent case, Esther discovers the importance of the GRDV, often the only recourse for the relatives of those who voluntarily disappeared.

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.