Thomas, 15, with shin cancer, enters hospital to get surgery. There, he meets Clément, his roommate, a regular of the place. Meanwhile, Sarah, a 13-year-old daddy's girl, faints in the middle of the schoolyard, while Mehdi arrives on a stretcher with multiple fractures after a motorcycle accident.

It’s the day of Thomas’s surgery. On the operating table, things are going as planned. For their part, Roxane and Clément find a way to pass the time while waiting for the end of the operation, and meet Mehdi. Sarah, meanwhile, is waiting to be changed to another room so she will no longer be next to Côme.

After having had a heart attack, Sarah is revived and taken for a CT scan, where she bumps into Clément. Roxane convinces Thomas to eat his meal tray to have the right to leave his room. They both sneak out of the hospital and find themselves alone for the first time. Nathalie, Côme's mother, has an interview to join the "The pink blouses" association.

Clément's results show that his tumor is still there. He has to go through some chemo sessions again but he no longer has the courage. To change his mind, Victor, a caregiver, offers to take him with Thomas to spend a day at the sea. During their absence, Clément's parents, devastated by their son’s relapse, meet Thomas’s father, Yves.

Sarah is allowed to go out for the day. Along with her father, she invites herself to a class rival's birthday party. Roxane, her mother, and her twin sister have an appointment with Dr. Sora. There is only a thirty percent chance that Clément new chemotherapy works. Dr. Catalan asks for Mehdi's grandfather to join so as to share the bad news.

Thomas has to deal with his father and stepmother's separation, Clément's grudge and Roxane's imminent departure . The Red Band Club decides to celebrate Roxane's last evening at the hospital. By playing "truth or dare", the last secrets are revealed within the Red Band Club.