In medieval times, an army of knights massacre a village of suspected witches and build a gigantic church over mass grave.
Now, in the present, the churches new librarian breaks the seal of the crypt, out of curiosity: an action unleashes the spirits beneath it, and triggers the church's ancient automated mechanisms which were installed by builders of the church to trap the spirits and everyone inside.
.
leaving everyone at the mercy of the reawakening demons!