The film begins in a dense forest where Anna lives with her guardian Gabe in isolation. Anna's curiosity about the outside world grows as Gabe restricts her from leaving the attic, filled with fear of wildlings. Gabe reveals Anna is the last human on Earth, protecting her from these creatures. On Anna's birthday, Gabe gives her a hamster, which becomes her friend until it dies. As Anna grows older, she suffers from Gabe's harmful medication and eventually asks for an end. Gabe, feeling guilty, commits suicide. Anna wakes in a hospital, learning her true identity and the effects of the medication.