When American high school student Emily plays with an Ouija board at a party, she becomes the unwilling host for a sadistic killer’s soul who held Westlake in a grip of gruesome terror. Its cause is an Ouija app programmed by the charismatic Owen, a rich kid obsessed with the supernatural. Now Emily’s boyfriend Tommy must team up with Owen, his rival for her affections and ex-best friend - and a defrocked Jesuit priest turned occult expert - to perform a dangerous, ad-hoc exorcism before Emily is consumed by evil and the demonic infection spreads through the school.