In the film the older sister becomes involved with an older Italian student who is determined to seduce her, while the younger sister is forced to conspire with the lovers, but harboring jealousy and similar desires.
but the end! oh the end is so bizarre!
the two sisters with their mother are sleeping at a rest stop(on their way back from a vacation) and suddenly a crazy man smashes the windshield with and axe! Then he axes the older sister in the head, strangles the mother and rapes the chubby younger sister. Two dead, one raped, end of film. What?!!