The high-kicking brothers go to stay with their grandfather over the summer to learn more martial arts techniques. During the visit they discover an unscrupulous corporation is dumping highly toxic waste on a Native American reservation, and decide to put their new-found skills to good use. Adventure sequel, starring Michael Treanor, Victor Wong and Charles Napier.

Rocky, Colt and TumTum must battle an evil wealthy toxic waste dumper in order to save a local Indian tribe and their friend Joe. The 3 Ninjas must help find Joe's father and find a secret disk that contains evidence that could stop the toxic landfill that is destroying the Indian community. However the town is owned by the rich man and he controls the police and even the mayor. They must fight a motorcycle gang and renegade cowboys in this non-stop ninja adventure.