After the death of her husband, Dr. Cara Harding’s (Julianne Moore) faith in God has been shaken, but not her belief in science. In an attempt to get her more open to accepting unexplainable psychiatric theories, her father (Jeffrey DeMunn) introduces her to Adam (Jonathan Rhys Meyers), a patient with multiple personalities who also takes on some of the physical characteristics of his other personalities. Cara quickly discovers that his other personalities were murder victims; and the more she finds out about Adam and his past, the closer she and her loved ones are to becoming victims themselves.