The film focuses on Nathan, a person who has multiple alters/personalities. Nathan knows that something is wrong with him. Through cases of lost time (whenever he switches to another alter, he loses time) and through conversations with his best friend, Cooper, he learns that his 'episodes' are impacting his life. The movie takes the audience through Nathan's daily life, until he is unexpectedly accused of beating his girlfriend (Nathan does not have a girlfriend), Marley. Nathan sits on the defense in a courtroom and we learn about Nathan's multiple personalities. We learn, after psychological testing, that Nathan has the disorder DID and we follow the implications of this throughout the rest of the film.
—Blitzer, Ryan