An end-of-the-world cult founded years ago when ten men colonised an island. It's a society in which men reign supreme, breeding is controlled, and knowledge of the outside world is kept to a minimum. Girls are wives-in-training: at the first sign of puberty, they must marry and have children. But until that point, every summer, island tradition dictates that the children live wildly: running free, making camps, sleeping on the beach. And it is at the end of one such summer that one of the youngest girls sees something so horrifying that life on the island can never be the same again.