A month after his wife's death, Max is tasked with investigating the disappearance of a teenage girl. Meanwhile, his daughter, Wendie, returns to high school and tries to resume her normal life with her friends. But a strange disappearance turns everything upside down.

While Max narrowly escapes death, Lucie and Jean-Guy investigate the violent and disconcerting attack on a minibus. Meanwhile, Wendie, Léa, and Nathan dig deeper into the symbol drawn by Mammig. But while they find valuable clues, they are trapped inside the retirement home...