It's another summer with Grandpa (Victor Wong), and Rocky (Michael Treanor), Colt (Max Elliott Slade) and Tum Tum (Chad Power) are ready for some serious ninja action. Trained by their lovable Grandpa, these young do-gooders befriend Jo (Crystle Lightning), a young Indian girl who confides that her father has been kidnapped by thugs hired by ruthless businessman Jack Harding (Charles Napier). It seems Dad has an incriminating computer disc related to Harding's illegal dumping of toxic waste on tribal land. The boys agree to help Jo find her father, and-armed with makeshift ninja weapons and in full war paint-set out to see that justice is done. By the time the dust settles, they have learned Grandpa's important lesson: flowers say nothing when they bloom, and true heroes don't need to boast about their deeds.