A distraught 21-year-old girl runs down a road at night and is hit by a car. When she woke up in the hospital, the police recognized, in horror, little Marina Masson, who had disappeared eleven years earlier.

Victoire thinks that the murdered man, Ivan Claes, is the one who kidnapped Marina. Marina secretly meets a mysterious young man, Maël, with whom she plans to run away. Laurent moves closer to his former family, Hélène and their three children reunited, leaving behind Selma, his young partner, and their son, little Liam.

Alex/Marina discovers the happiness of having a family and a loving mother, which makes his little sister Eléonore very jealous. She makes the decision to become Marina for good and gives a great interview on television. She breaks up with her boyfriend, Maël, but not before giving him all the money her mother has collected for her. But she discovers that Laurent suspects her of lying and has secretly launched another DNA test. Thanks to Marina's little ghost, Laurent finds proof that Marina is indeed dead, and her murderer is still in the wild. But Victoire doesn't believe it. Laurent confides in Selma that he is going to set out on his own on the trail of his daughter's killer.

A mysterious caller contacts Alex/Marina and threatens her: he knows her identity and will report her to the police if she doesn't do everything he tells her. As Laurent and Hélène grow closer and closer and end up making love again, Jonathan and Alex/Marina fall in love. As for Eléonore, she introduces her new flirt to her family: it's Maël, who hid his identity from her! Alex/Marina is appalled. Victoire discovers that Laurent Masson was right: Ivan Claes is innocent and little Marina's killer is manipulating them in the shadows, very close to them. Laurent confronts Alex/Marina about his lies. Now they will investigate together because he has a way to find the one who killed his daughter: it's her!

Hélène confesses to Laurent and Alex/Marina that at the time of Marina's disappearance, she had a lover. Because she had surprised them, the little girl had run away and been kidnapped. Hélène confesses to Alex/Marina that she was incredibly jealous of her complicity with Laurent and that mother and daughter had a very difficult relationship. Jonathan and Alex/Marina are more and more in love. Laurent confesses to Selma that he cheated on her with Hélène and she kicks him out. Victoire doesn't let go of Laurent because she knows he wants to take justice into his own hands. Marina's killer has been playing with the police all along to direct suspicion towards Ivan Claes. Horrified, Victoire discovers that the man manipulating them is none other than Paul, Laurent's best friend.

Laurent finds a blood-stained towel and Marina's bracelet in Ivan Claes' secret safe. He entrusts them to Paul for analysis, but Paul hastens to burn them. Having dragged him into an isolated forest, Laurent threatens to shoot Paul in the temple if he doesn't confess where he buried his daughter. But Paul is not the culprit. He was only trying to protect his son Jonathan. He was the one who killed Marina. Hélène is left by her fiancé, Sully, a member of her group of parents of missing children. Sully has understood that Hélène will never share his love and he prefers to leave. Paul goes to warn his son Jonathan that he must flee urgently because Laurent is looking for him to kill him. Jonathan screams his innocence and refuses to flee.

Alex is visited by her real mother, Sylvie, who abandoned her without a word when she was a toddler. Laurent has found his daughter's killer. He carries him on his boat and goes to the open sea to torture him. When he removes the hood that hides the sobbing man's face, we recognize Sully, Hélène's friend. Laurent tortures him all night to make him confess the truth. He is a sick man, a pedophile, he raped and killed little Marina eleven years ago. Alex goes to Jonathan's hotel to declare his love for him and wants to have sex with him, but Jonathan is furious at all of Alex's lies and rejects her. Hélène discovers that Eléonore has run away with Maël. Her older brother Loïc and Alex manage to find Eléonore and bring her home. Victoire understands that it is Sully who has been kidnapped by Laurent. Laurent, at his wit's end, ends up killing Sully. Victoire rushes to the coastguard boat but she can't find Laurent's boat.

Arrested by Victoire after his return to port, Laurent denies killing Sully. He went fishing and fish blood obscured any trace that the police might have found. However, Victoire is convinced that he has accomplished his revenge and will do everything to prove it. Helen reveals to Alex that she's figured out for a while that she's not Marina. Alex is reluctant to join his real mother Sylvie, but Hélène asks him not to leave. Marina doesn't go to the appointment with Sylvie. Selma doesn't want her son to grow up without a father and agrees to let Laurent come back. Alex confesses to the press that she is not Marina and that she has stolen the place of a missing child. Selma asks Laurent to go and denounce himself because they will never be able to live with this lie. Victoire was waiting for him. Laurent is imprisoned.