Three smart and young kids live in the remote mountains with their grandfather, practising the kung fu arts. The four of them live entirely isolated from civilized society. One day, the kids release their grandfather's pet bird by mistake. Fearing punishment, they run away to the city, intending to stay with their grandmother.

Once in the city, they are captivated by it. Having no money, they are taken advantage of by a dope peddler who leads them into the world of crime, controlled by a drug ring. Realising their mistake, they escape and are rescued in the nick of time by their grandmother. The drug ring retaliates by kidnapping the old lady's grand-daughter.

The three kids spring into action to save the little girl. At the moment of their greatest danger, grandfather appears and saves the day.

The kids and grandparents are happily reunited, and the criminals are jailed.