Each year, three brothers Samuel, Jeffrey and Michael Douglas visits their Japanese grandfather, Mori Shintaro whom the boys affectionately refer to as Grandpa, for the summer. Mori is a highly skilled in the fields of Martial arts and Ninjutsu, and for years he has trained the boys in his techniques. After an organized crime ring proves to be too much for the FBI, it's time for the 3 brother NINJAS! To use their martial arts skills, they team up to battle the crime ring and outwit some very persistent kidnappers!

To escape his life of crime, a Paris drug dealer takes on one last job involving Spain, unhinged gangsters, his longtime crush and his scheming mother.

In an underground fight club, blackbelt Travis Brickley is killed after losing to the evil martial arts master Brakus. Travis' death is witnessed by Walter Grady, the son of his best friend Alex Grady. Alex and his partner, Tommy Lee, vow to avenge their friend's death by defeating Brakus and shutting down the fight club.

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.