In a Gothic cathedral built on the mass grave of a Teutonic purge, an ancient discovery by the new librarian will release an unholy maelstrom of madness, violence, and demonic vengeance. A mysterious parchment carrying what resemble architectural schematics sets off a chain reaction, unleashing demonic forces that attack the church occupants, leading to increasingly elaborate and deadly visions, as well as violent possession and gruesome deaths. As the survivors try to find a way out, they uncover dark secrets about the church's creation and the true purpose of its architect, who was left to die in the building.