On a new assignment, Rose takes a special liking to one of her students, Lisa; when she realizes Lisa is being abused at home, Rose tries to alert social services, but no one, not even her partner Mehdi, seems to care about Lisa's fate.

Rose and Lisa arrive in Bordeaux; Rose is reunited with her adoptive mother and her two sisters, Garance and Melanie, whom she has not seen for a decade; in Saint-Nazaire, Baranski and Valin try to solve the mystery of Lisa's disappearance.

Garance and Melanie discover the existence of Lisa, who calls herself Charlotte, and whom Rose passes off as her daughter; Isabel resists Daniel's advances as best she can; in Saint-Nazaire, Baranski and Valin discover that Lisa has been kidnapped.

Determined to get her daughter back, Julie bursts into Isabel's house; Garance learns that it was Rose who kidnapped the girl wanted by the police in Saint-Nazaire; Greg intends to retrieve the drugs he hid in Lisa's blanket.

Greg a enlevé Lisa. Rose et Mehdi partent à sa recherche. De son côté, Julie apprend à la police que c'est Rose qui a enlevé sa fille. La brigade part immédiatement pour Bordeaux. Rose fait ses adieux à Isabel.

Hunted by the police, Rose, Medhi and Lisa find brief refuge in an abandoned fortress, but they are quickly surrounded by the police; Rose is arrested and Lisa placed in a home; a year later, Rose's trial takes place.