When Tommy was a boy, he saw his grandpa (Hy Pyke) the leader of a vicious satanic cult, murder his father in a brutal ritual on Halloween night. Now Tommy (Gregory Scott Cummins) is 18 and grandpa is ready to indoctrinate him into the ways of the black arts. But as night approaches, someone dressed like a member of the cult, whose face is hidden behind a devilish mask, begins talking and killing people connected to Tommy. Could it be grandpa, Tommy himself, or someone even more sinister behind these increasingly brutal murders?