Fifteen-year-old Fern lives in London, and this city is not the best place for her. She feels like a stranger even in her own family and is used to trusting only herself. She has a twin brother - they are connected not only by blood, but also by mutual... hatred. However, the day comes when everything changes: Fern is faced with the secret of her long-dead mother’s past, and a wonderful world born of dreams and daydreams opens up before the girl - Annwn, under the protection of an ancient knightly order. But this world is fragile, it is threatened by cruel nightmares, and it becomes increasingly difficult for the knights to overcome them. Fern learns that her brother Ollie is to join the order and does everything she can to prove that she is worthy too. Gradually, Fern realizes that the danger lurking inside the dream is more insidious and terrible than any nightmare. After all, the ability to influence someone’s dreams means the ability to control other people’s thoughts...