In 1980s Hong Kong, troubled youth Chan Lok-kwun accidentally enters the notorious Kowloon Walled City. Lok-kwun, a refugee from the mainland, struggles to survive by participating in underground fighting rings. He seeks to buy a fake ID to improve his life but is betrayed by Mr. Big, a local crime syndicate boss. In a desperate move, Lok-kwun steals drugs from Mr. Big and flees to the Walled City, where he encounters Cyclone, the local crime lord who rules the area with a mix of authority and compassion.