Skinned Deep (2004)

The horror film Skinned Deep begins when a family suffers a flat tire on a barren stretch of road with only a diner dotting the landscape. They meet Granny, the seemingly nice old woman who runs the establishment, but they soon find that she is the leader of a deranged clan. The family is slain, with the exception of their teenage daughter, Tina whom one of the sons in the family, Brain (a boy with an externalized brain much larger than his head), takes a romantic interest in. Soon a group of bikers show up, forcing the girl to figure out which group of crazies she should throw in with in order to stay alive.