In 1977, a serial rapist struck Ohio State University. Overwhelming evidence soon led investigators to Billy Milligan, an aimless young man with a traumatic childhood and a criminal record. But when he was arrested, Billy couldn't remember anything about the assaults, and his reactions seemed to change often. The psychiatrists diagnosed him with multiple personality disorder and eventually determined that there were as many as 24 different personalities in his mind. But his lawyers appealed. With the help of friends and family, Billy went on the run and changed his identity...