The Kung Fu Kids want to live in the city with their grandmother. Grandpa, however, disagrees. He fights a duel with grandma in order to decide. Grandmother wins.

In the city, they enroll in a school where they excel at physical exercise because of their kung fu training.

Grandpa meets an old friend and they enter an inn where a martial arts contest is taking place. A gang of kung fu experts challenges grandpa to a duel. On the day of the match, grandpa is unwittingly drugged and cannot sustain his strength. The old man is missing.

The kids resolve to train hard in order to rescue grandfather. They challenge the kung fu experts and invade their headquarters. The kids find their grandfather. Together, they defeat the hoodlums.