On the eve of her 17th birthday, Mari and friend Phyllis set off from her family home to attend a rock concert in the city. Attempting to score some drugs on the way, the pair run afoul of a group of vicious crooks, headed up by the sadistic Krug. Two teenage girls heading to a rock concert for one's birthday try to score marijuana in the city, where they are kidnapped and brutalized by a gang of psychopathic convicts.