Lyon, June 21, Music Day. Leah Morel is preparing to celebrate her 17th birthday with her cousin Chris and his friends. At dawn, Leah is still not back and her mother's anger turns into anxiety.

Julien fiercely denies any suspicious or incestuous relations with his daughter. He has lied about his whereabouts to protect his wife Florence because he was being harassed by Anne, a former mistress. Leah disappeared when he was driving the woman home... Anne had come to the restaurant to try and talk to Julien, and she will be able to confirm his alibi.

Leah’s frightened message revives the hope of her family that she is alive, she must have been abducted. Tracing the signal of the last call made from Leah’s phone leads Molina and Camille to the train station. Is Lea being held somewhere in the neighbourhood? Molina decides to focus the resources there, but Julian, who feels excluded from the case, thinks it’s a mistake to stop searching the park.

With Nicolas (waiter) closely following the investigation through an illegal police scanner radio, Julien is warned that Dupuis has just revealed to the police where a body has been buried...

A body has been found... Meanwhile, the police continue to investigate the disappearance of Lea, finding a list of people she invited to her birthday party. One name on the list has not yet been accounted for.

Everybody is shocked by Nicholas’ confession. Flo focuses on Zoe's birthday party in an attempt to get on with life. Chris, who is an increasing presence in the household, lends her support.