The Exorcism of Emily Rose is ostensibly based on the story of Anneliese Michel, a German college student who believed she was possessed by multiple demons, including Lucifer, Nero, Judas Iscariot and Adolf Hitler.

Emily Rose is a 19-year-old farm girl who began having strange visions and convulsions while away at university and was diagnosed as a psychotic epileptic. But when her medications didn't stop her terrifying outbursts, she turned to Father Moore, who attempted an exorcism with the approval of the Catholic Church. He told Emily to stop taking her pills - which led to his charge in her eventual death.

Ambitious Erin, a junior partner in a law firm, is a rising star after getting a high-profile murderer off the hook; when asked to take on the case of Father Richard Moore, she accepts with the proviso that she'll make senior partner if she wins. Standing in her way is prosecutor Ethan Thomas, a self-professed man of God who nonetheless ridicules Moore's beliefs in a case that quickly becomes a debate between science and faith.