Concerned about the future of her unborn child, a pregnant woman argues with her husband to end the association with a satanic sect they both have. Their confrontation results in a murder-suicide. When a new family moves into the house where the couple lived, the spirits of the deceased take over the bodies of teenagers, Dan and Tracy. Possessed by these demons, the children’s behavior becomes increasingly out of control. The parents, Janet and Allen, assume their children are going through a rebellious fragment of their adolescence. However, as things get worse, Janet learns that the problem is subhuman, but Allen refuses to believe that explanation. Accepting that the children are losing their battle with the devil and that their lives are in jeopardy, Janet turns to the Church for help, against the wishes of her disbelieving husband. With the demons exercising their evil powers, the only way to save the children is to perform an exorcism, which has horrific consequences and a startling conclusion.