A young woman is committed to a mental hospital for treatment of multiple personality disorder. While there, she is treated with an experimental new procedure dubbed "The Siamese Burn", designed to eliminate all, but one of her personalities. After the treatment she is moved to a halfway house to continue her recovery. While she is there, the other residents of the house begin to die at an alarming rate, and she is left to wonder after her treatment; which one of her personalities was the survivor?