Siblings Ah Ling (Patricia Chong) and Ah Wah (Eddie Chan) join a fresh-faced group of city teens to take a weekend camping trip in the mountains outside of Hong Kong. Alas, the villagers don't care for visitors, much, and a group of vile, thuggish, "disco boys" have taken up residence in town, where they steal hens, hunt and butcher wild boar, and drink snake blood. They also like to rape girls, as no doubt consensual sex is pretty much out of the question for them. When these beasts run into the campers, the encounter leaves one girl brutalized and insane, and another camper impaled on a boar trap. When the police are unable to convict the gang, the teens father (Chan Sing) takes it upon himself to make sure justice is served.

The Iga and Koga ninja are at each other's throats again, this time because Dr. Kikuchi, head of the Iga ninja, has developed a serum that cures everything, and an evil arch-villain named Brian (Waise Lee) wants it, and has the Koga kill Kikuchi to get it. Only trouble is, the serum is in a box that can only be opened by the "key" -- an unemployed, flute-playing street musician named Copy (Dayo Wong). Purple, red, and green-clad ninjas led by Hong Kong action veteran Eddy Ko hop about trying to save, kill, or kidnap Copy.