An eighteen-year-old girl murders both her parents. When she's arrested, she behaves as if possessed, flinging her body around erratically and speaking in tongues. She behaves the same way at her arraignment, and the judge assigns her to psychiatrist David Rothberg to determine if she's fit to stand trial, or if she's insane. In treatment, she claims the Devil ordered her to kill her folks, but beyond that she's a complete mystery to David. Meanwhile, a transgender woman is killed in a men's room by a misogynistic cop. David's close friend Detective Perryman is intent on catching the killer. These two cases run parallel to each other, and result in shocking ends to both investigations