The three unstoppable ninja brothers, Rocky, Colt, and Tum Tum, take a vacation to the Mega Mountain amusement park where they look forward to seeing their favorite TV action superstar, Dave Dragon. While the brothers are enjoying themselves, the evil bandit queen Medusa and her vicious chief henchman, Lothar Zogg, take over the park by force of arms. Medusa demands a ransom of $10 million. Tum Tum spots Dave Dragon being captured. He gets his ninja brothers and they go into action, using their considerable fighting skills to battle Medusa and her criminal cohorts. Rescuing their hero, they fight together to retake the park and rescue all the people in it.