Charlie, a discreet cop with little ambition, is hit by a car. When she wakes up, she's bursting with energy. Previously confined to the complaints desk, she joins Chris's investigation for the first time, to find a missing little girl, Anna. Taking Samy, the squad's new trainee, with her, Charlie sets out to find the yoga centre where Anna and her mother live. Together, they discover that Anna's mother is trying to free herself from the grip of her husband Fabrice, who runs the holistic centre with its sectarian overtones. And when the duo realise that Anna has diabetes, everything becomes clear: the little girl has not been kidnapped but hidden away by her mother, who wants her to be treated by a real doctor, in secret from Fabrice.

Charlie is the only one to take the father of 22-year-old influencer K-Lista seriously when he reports her missing at the police station. She and Samy go to their home to make the initial findings and find a trail of blood. While Chris immediately suspects K-lista's father, Charlie delves into her social networks to find out who the victim was. With Samy, she explores the underbelly of the world of influence and becomes convinced that it was a deliberate disappearance, deliberately orchestrated to create a buzz. But K-Lista's lifeless body is found, proving Chris right. Alone against the rest of the brigade, Charlie and Samy must do everything they can to prove that it was, in fact, Eva, K-Lista's timid assistant, who murdered her boss to take her place.

Nicolas, a childhood friend of Charlie's, calls him for help after a car accident, tragic for Anthony, his sister's husband, who was at the wheel. Fatal accident or sabotage? When they discover that Anthony was leading a double life and that his wife was in debt, Charlie and Chris agree for the first time: she murdered her husband to collect the insurance money. Plunged into the world of classic cars, Charlie enlists the help of Muriel, the energetic sister of Inspector Billon, a former cop who has gone into private practice, thus alienating the rest of the brigade. Once the investigation has come to a standstill, she can only count on Samy to follow her, and together they will discover that Anthony is, in fact, alive and well: it is he who, with Nicolas's help, has organised a life insurance scam to save his wife, who is gravely ill with heart disease.

Determined to find her half-sister, Charlie sets off for London, accompanied by Samy. While visiting the Sherlock Holmes Museum, Charlie meets Tracy Sheraton, a psychotic girl who begs her for help: her sister's ghost has come to warn her that she is in great danger. For her parents, Betty - a famous actress - and Joseph - a devoted stay-at-home dad - Tracy's erratic behaviour resembles in every way the first signs of dementia in their eldest daughter Emma, who committed suicide three years earlier. Weakened by a meeting with April Moriarty, her half-sister, which doesn't go as well as she'd hoped, Charlie takes refuge in Samy's arms, but is soon caught up in the investigation. She must save Tracy. Samy's medical skills come in handy now more than ever to prove that Tracy is not crazy and that Emma is still alive. They save Tracy from internment by proving that the Sheraton girls were poisoned by their father.

Jiyoung, a young ice cream master, is found frozen to death in the freezer of the ice cream factory where she works. While Chris investigates the victim's stormy working relationship, Charlie tries to find out who Jiyoung was and discovers that the crime scene was an impromptu cryotherapy session gone wrong. The investigation eventually reveals that Jiyoung was having an extramarital affair with Vincent, the factory manager, who moves to the top of Chris's list of suspects. Charlie is left in the lurch by Samy, who has had a hard time of it with Charlie since their return from London, and is unable to convince Chris of Vincent's innocence. She needs all her energy to get to the bottom of the matter and reconcile with Samy. The two of them arrive just in time to prevent the real culprit, none other than Vincent's daughter, from committing the irreparable act. The latter will eventually confess: after discovering Jiyoung's affair with her father and seeing her family destroyed, she took advantage of one of her cryotherapy sessions to lock Jiyoung in the freezer.

George is in a coma after an attempted murder. The station mobilises to support Charlie and find the killer. While Chris investigates a burglary gone wrong, Billon tries to keep Charlie away by assigning her to a parcel theft investigation. But this is to misunderstand Charlie, who, with Samy's help, is determined to get to the bottom of the attempted murder of her grandfather, behind the backs of the rest of the brigade. She soon discovers that the various clues incriminate her. A race against time begins to stay one step ahead of Chris's investigation, but doubt gradually creeps in: could Charlie really have attacked George? It's thanks to the trust and support of Samy, who doesn't believe for a second in her guilt, that Charlie manages to foil the trap that has been set for her. She finally tracks down the culprit, her half-sister April Moriarty, whom she finally confronts. But just when she thinks she has finally uncovered the truth, Charlie has to confront new secrets from the past.