Railway Security officers Shek Fung and his female counterpart Lau Ching ran into their old friends Cheung Hung Wai and Li Ting while carrying out their duties on board a train. As it turned out, Cheung Hung Wai is a dangerous criminal and is being chased Train Police Officers Shuet Mui and Cheung Siu Man. Meanwhile, Railway Security Bureau Chief Chow Chung Lam has drawn up a wonderful plan to catch the criminals, Shek Fung and Li Ching as undercover agents. Shek Fung now knowing Cheung Hung Wai being a wanted criminal with a briefcase full of explosives in his possession immediately ordered the train to be stopped. The two had a fight and in the midst of the argument, Shek Fung was shot whilst Li Ting was arrested however Cheung Hung Wai escaped on board the train….