On an isolated island off Scotland, six teenagers wake up alone in their boarding school: supervisors and teachers mysteriously disappeared. At first glad to be free from all constraints, they finally take the road, in search of answers. In front of them the apocalypse gradually takes shape: infected by an unknown virus, the inhabitants have turned into bloodthirsty predators. Worse, the scourge seems to affect only adults. Now, to survive, the group must answer two questions: how to leave the island? And at what age do we become adults?