Summer, 13, lives with her sister Alyah, 15. Following the death of their mother, the two girls were raised by their survivalist father in nature far from the contemporary world. Summer, shy and withdrawn, idolizes Alyah who has one obsession: protect her from the outside world. When Alyah causes an accident with a policeman to "protect her family", their father takes the blame and is imprisoned. Shocked, the girls are forced to go and live with their aunt Valérie who has been desperately looking for them for years. Unable to adjust to their new family, Alyah wants to flee and join their stepmother Myriam. But Summer is torn between her desire to emancipate herself from her sister and the fear of breaking their fusional love. Summer will make a choice: let Alyah go at the risk of losing her.