It's Native American Summer Days in Indian Falls, and Rebecca Robbins is roped into taking a turn in the Senior Center dunk tank. That is, until her rhinestone-studded grandfather Pop needs help setting up his Elvis act. Minutes from climbing into the tank, Rebecca has to find a replacement. Roller derby girl Sherlene-n-Mean takes her place, and is promptly electrocuted and killed. It's obvious to the police and Rebecca that this was no accident, and no one knows who the murderer's intended target was. With Pop cheering her on and aided by a trio of self-appointed bodyguard derby girls, Rebecca digs for answers, dodges bullets, and races to find a killer.