بعد أن قام سام وهو صاحب عائلة من لندن بإنقاذ فتاة صغيرة مضطربة في الغابة قام بإعادتها إلى منزلها في جزيرة أوسيا المشؤومة حيث يستعد السكان لمهرجان سنوي مثير للفضول عن تاريخ الجزيرة

Plagued by a disturbing dream, Sam awakes to find himself in a compromising situation and, having missed the morning crossing to return to the mainland, spends the day trying to learn more about the islanders’ beliefs. After a series of confusing and terrifying events leaves him shaken, Sam quickly plots a way off Osea with Jess, but is convinced to stay put as the islanders prepare for a dry run of their big event.

Sam is shocked to learn the truth about his connection to Osea and the islanders’ intentions for his future. Later, in a fight for his life, Sam tries desperately to escape their clutches and make it back to the mainland in one piece.