A flat tire in the middle of nowhere forces the Rockwell family to seek help at a nearby ramshackle diner. The diner is run by Granny, who is actually the insane matriarch of a group of mutants led by the imposing and metal-faced Surgeon General, as well as the demented "Plates" (Davis). The entire Rockwell family is murdered with the exception of the teenaged Tina, who is chosen by "Brain" to be his future wife. When a gang of aging but still murderous motorcyclists enters the picture, Tina has to choose sides to save her life - and this clearly is a tough choice to make.