A 19-year-old searches for her twin brother after he runs away from home, following a fight with their father.

Camille arrives in Ouessant, the island of her birth off the Brittany coast, to sell the family home. She spends a last night in the house during which she discovers a secret. In 1963 a man came to work with her father, who was the Jument lighthouse operator. He only stayed two months, but his presence proved to be a disturbing catalyst.