Cillian Murphy, Ellen Page and Susan Sarandon star in this psychological thriller about a man with a split personality disorder. Shy bank employee John Skillpa (Murphy) lives in the small community of Peacock, Nebraska. Following a traumatic childhood experience, he suffers from dissociative identity disorder with his alter ego being a woman called Emma. He manages to keep his problem a secret until one day, while Emma is out in the garden, a derailed train crashes onto John's land. His neighbours rush to the scene of the accident and meet Emma for the first time. When questions are asked, John declares that Emma is his wife but now that the townspeople know of her existence it becomes much harder to keep the truth about her identity from them. To make matters worse, young, single mother Maggie (Page) ignites an internal battle in John and Emma that becomes ever more present. Will she take over John completely?