Sally LaChance leads a double life. By day, she works as a park ranger in a midsized Missouri town. At night, she acts as emcee for the local roller derby team, the Boonslick Bombers, at the Empire Roller Rink. Sally loses her temper one day and pulls a gun on a group of polluters in Karst Park. Her boyfriend captures the moment on film and posts the footage to YouTube, putting Sally's job, her relationships, and her life at risk.