Helene, 15, lives with her younger sister and brother and their parents in a house near a river with an island. School is out for the summer, it's hard to find things to do to ward off boredom, but Helene finds work in a garage. A girl her age has gone missing and, eventually, her murdered body is found on the island, l'ile de la merci. In this atmosphere of violence and fear, Helene tries to understand the silences in her house, the sexual yearnings...