A young woman moves to Paris and has a brush with disaster. Grown-up at last, an accomplished woman thought she was safe from her own past. Gradually, these characters come together to form a single heroine.

Mathilde, aged 9, enjoys her last day of summer holidays at the seaside with her group of friends. Her father falsely interprets one of their games.

Cutting himself off from the world, his friends and especially his father, against whom he nourishes feelings of bitterness, resentment and distrust, Thomas, a 12-year-old boy, becomes increasingly and mysteriously obsessed with swimming and diving in the local swimming pool.