When teenager Lea Morel does not return home from a music festival, her desperate parents contact the police. Lieutenant Molina, freshly transferred from Paris, uncovers areas of Lea’s life that her family knows nothing about.
Lea’s father Julien is in police custody for lying about his alibi and refusing to give his actual whereabouts on the night of his daughter’s disappearance. Molina and Camille discover that Lea has been introduced to single-seater racing, but wonder how she managed to pay for lessons.
Julien is woken by a frantic message on his mobile phone from Lea asking him to call her. Molina and his team trace the call to the train station. Nicolas, a waiter at Morel and Sons restaurant, shows Julien the illegal police radio interceptor he has in his car, and as Julien listens to the communications, he begins to shadow their investigations.
Francis Dupuis is interrogated, but he is obviously confused and unclear about details. However, when the police search his property they make a surprising and convincing discovery.
The waiting is finally over for the Morel family. Julien becomes obsessed with with the photos taken at Lea’s birthday party and is determined to identify everyone who attended.
An apparent suicide with a long confession seemingly concludes the case, but Molina is not convinced. Chris helps the Morels deal with their loss, and Tom gives Zoe a gift that softens her anger against him.
A jeweller identifies the man who bought the pendant. The man is questioned, but he has an alibi. Romain is given a bag of Lea’s possessions left at the race track that show him a secret part of Lea’s. The Morels marriage starts to crumble.
Molina decides that the police have been chasing a red herring and retraces their investigation into Nicolas Barrault. A search of his possessions turns up one of Jenny’s business cards with a handwritten note on the back.