A group of college students on holiday become prey for a killer and his two sadistic and demented sons. One son, an unlicensed doctor, is mentally unhinged by destructive brain parasites. The other son, a shy and lonely psychopath, falls in love with a dead girl. While the insane boys and blundering through their destructive rampage, the father stalks the night with random violence. Though he is shot, beaten, and run over by a car, the maniac cannot be defeated. One by one the students enter the horror house, where they must face the malignant forces left behind by unnatural scientific experiments.