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This is the fourth in the 3 Ninjas action-adventure series with retired ninja Grandpa Mori (Victor Wong) as the connective device linking all four films. Following the low-rent 3 Ninjas Knuckle Up (a 1992 production which went unreleased until 1995), the fourth boosts the budget and features three new lead youngsters plus assorted "guest stars." Grandpa Mori teaches martial arts to his three grandchildren: 15-year-old Rocky (Mathew Botuchis), 14-year-old Colt (Michael J. O'Laskey II), and 8-year-old Tum Tum (J.P. Roeske II). On a trip to the Mega Mountain amusement park, the three boys are joined by their computer genius neighbor, 13-year-old Amanda (Chelsey Earlywine), daughter of a movie special FX designer. The villainous Medusa (Loni Anderson) leads a ninja army to Mega Mountain. With her head henchman Lothar (Jim Varney), Medusa intends to move into Mega Mountain's master control center and hold the park patrons for a $10 million ransom. However, former TV star Dave Dragon (Hulk Hogan) happens to be making an appearance at the park, and the combination of Dave, Rocky, Colt, Tum Tum, and Amanda makes life difficult for Medusa and her warriors.