The children of a rural cult decide to open a locked door that their families have sworn to protect. Opening the door unleashes The Brute, a terrifying, supernatural creature. The monster devours Ben, the boy who opened the door, and quickly goes on a rampage through the compound, picking off cult members one-by-one. Carrie, the last child alive in the cult, manages to close the door, but not before losing both parents and her left arm.