We go back 25 years and finally experience the events from Vinca's point of view. Back in the present, Annabelle confronts DeVille with a gun about the attacks on Francis, Ahmed and Max.

Thomas is in mourning. His real father, Francis, is dead, and his half-brother, Max is in a coma. Annabelle is nowhere to be found but has left directions for each of the remaining protagonists. For Thomas, get in touch with Fanny who will be able to provide him with the answers he needs.

The secret is now too heavy for Thomas and Maxime to bear. They confess to Annabelle that they murdered an innocent man. Francis, meanwhile, is still being tortured by this masked individual he now calls Alexis. An old article from the student newspaper reminds Thomas of the strange past resemblance between Fanny and Vinca. Thomas understands that he is not the only one plagued by secrets. A confrontation with his mother Annabelle, will come to question his whole existence...

Francis is kidnapped from his home by a masked individual. Fanny confesses to Thomas that she was Vinca's accomplice. She asked him to take pictures of her and Richard in order to blackmail him. For his part, Maxime is under pressure from the "unreliable friends" of his father Francis. His father being unreachable, it is now up to Maxime to repay this debt. Pianelli learns from hospital staff that Ahmed died shortly after conjuring up a body in the gymnasium wall. Suspicion immediately turns to Fanny...

Thomas and Maxime in a panic, rush to see Francis. A sports bag containing 100,000 francs is discovered by Manon. A person seems obstinate in digging up events from the past. So much so that Thomas finds an envelope on his car containing photos dating back 25 years that reveal a relationship between his father and Vinca.

Once inseparable, Fanny, Thomas and Maxime have never spoken to each other since Vinca disappeared that winter night in 1997. We soon learn that that same night Vinca disappeared, Thomas and Maxime murdered their philosophy teacher, Alexis Clément. . Maxime's father, Francis, and his right-hand man Ahmed, immured the body in the high school gymnasium which will be destroyed in the coming days. When, 25 years later, Thomas decides to break this silence by going to a reunion of former students of the Saint-Exupéry high school, he will, without knowing it, put the lives of all those around him in danger, start with that of Maxime. How will the two friends manage to cope with the situation?