Kao Chiu has invited an expert in gunpowder to the capital city, knowing that the secret of explosives and cannons will give him the crucial edge in his battle against Lin Chung and the honourable rebels. Unfortunately for Kao, the man and his son are attacked by bandits, and seek refuge at Liang Shan Po. Lin Chung and the rebel knights must persuade the man to stay and teach them the secret of gunpowder, for it is unthinkable that such weapons should fall into the wrong hands.