Summer in the French Alps. 15-year-old Lise meets up with her half-brother Simon, who, at 18, has moved back to live in the region with his mother. He fits in well with her group of friends and her boyfriend Kevin. One day Lise takes him to Dramonasc, the abandoned hamlet of their ancestors.

L'été, dans les Alpes. Un soir de bal, Lise, 16 ans, voit une bande de jeunes s'en prendre violemment à Simon. En treize fragment, leur passioni cachée va se déployer comme un poison au coeur des montagnes.