Recruited to replace a renowned psychiatrist who has mysteriously disappeared, Dr. Rachel Miller is plunged into the hectic world of psychiatry at a state-of-the-art clinic specializing in the treatment of dissociative identity disorder, also known as multiple personality disorder. When one of her patients commits suicide under suspicious circumstances, Rachel begins to question her abilities and whether she has made the right career choice. Her doubts are soon replaced by fear as she suspects that her colleagues and their unorthodox methods of treatment are behind the violent suicide. Rachel's fears are shared by Ed Morgan, an insurance agent sent to assess the clinic's insurance needs, after he makes a startling discovery. Enlisting the aid of a patient, an enigmatic ex-CIA agent, and a tenacious FBI agent searching for the missing psychiatrist, Rachel and Ed dig deeper into the clinic's origins, only to discover that the clinic has as many secrets as its patients.