Following the reappearance of 16-year-old Anna Casteran, who disappeared 5 years ago, the police are deploying considerable resources to find Lucie Perez.

Anna Casteran finds it difficult to cooperate with the investigators. The police come face to face with the fathers of the Perez and Casteran families, who disrupt the investigation.

A half-burnt flamenco shoe, takes our investigators to the other side of the Spanish border. Alix and Balthus are caught up in their mission.

As the TV show on Anna's return gets underway, Alix and Victor gradually realize that Balthus no longer in touch.

Alix leaps on her motorcycle into the forest in pursuit of a suspect on a quad bike... The investigation has taken on a whole new dimension, and the law enforcement responded immediately.

A breakthrough in the search for Lucie Perez leads to an explosion. The valley holds its breath. Despite the intensity of the shock, the investigators decide to take risks in order to speed up their investigations.