Clyde et Stephanie Brenek ne voient pas de raison de s’inquiéter lorsque leur fille cadette Em devient étrangement obsédée par un petit coffre en bois acheté lors d’un vide grenier. Mais rapidement, son comportement devient de plus en plus agressif et le couple suspecte la présence d’une force malveillante autour d’eux. Ils découvrent alors que la boîte fut créée afin de contenir un Dibbuk, un esprit qui habite et dévore finalement son hôte humain.
The basketball coach Clyde and his wife Stephanie divorced a couple of months ago and their teenage daughter Hannah and the girl Emily 'Em' live with their mother and spend the weekends with their father. One day, Clyde stops his car in a yard sale and Em buys an antique carved box and becomes obsessed with it. Em finds the hidden lock and releases an evil spirit that possesses her. Soon Clyde discovers that Em has a problem, but his annoying ex-wife and her boyfriend Brett do not pay attention to him and get a restraining order against Clyde. Clyde seeks out Professor McMannis and when he sees the box, he explains that it is a Dibbuk Box, where a fiend is trapped inside. He also explains that the box should not be open; otherwise the person will be possessed by the spirit. Now Clyde travels to a Jewish community in New York and the rabbi's son Tzadok returns with him expecting to exorcise Em to save the girl.