Sydney, a woman with a severe multiple personality disorder stemming from a traumatic childhood experience, seeks the psychologist Dr. Lewis. Together, Lewis and Sydney attempt to purge Sydney's "alternate" personalities so she can live a normal life. Lewis provides encouragement while Sydney wanders the dark hallways of her mind, confronting and eliminating her other personalities. Progress is made, but it is not without problems. Sydney finds that purging her personalities is not easy, and often has severe relapses. One night when she leaves, a group of heckling teenagers provokes a violent, aggressive personality out of hiding, and she attacks the teens. Sydney continues working harder than ever... but is there something that her mind is not revealing to her?