After a 13-year imprisonment in Hong Kong, a kickboxer challenges the current champion in order to restore his honor.

A young man adopted by a renowned swordsmith, discovers that his real father was killed by a powerful bandit called Lung. Leaving to seek revenge, he runs foul of a group of vicious desert scum, losing his right arm in the process. After being nursed back to health, he eventually learns to compensate for his loss and returns to confront the man who murdered his father.

Siu, who spends goofing off, finds out that he has Parkinson's Disease, and only one month to live. He decides to do something special before his death. He tries to help other, and accept challenges.

The story of Ho, a Chinese peasant/slave worker who escapes to Hong Kong and becomes one of the most feared crime bosses in Hong Kong.

The final entry in Michael and Johnny Mak's Long Arm of the Law series, Underground Express once again tells a story of gangsters versus police, focusing on the difference between how both factions act depending if they're coming from Hong Kong or Mainland China.