The War to End All Wars (S02E07)

Kao Chiu has summoned a gunpowder expert to the capital, believing that knowledge of explosives and cannons will provide him with a significant advantage over Lin Chung and the noble rebels. However, the expert and his son are ambushed by bandits and manage to escape to Liang Shan Po. Lin Chung and the rebel knights need to convince the man to remain with them and share his knowledge of gunpowder, as it's imperative that such powerful weapons do not end up in the hands of their enemies.