During the 1980s in Hong Kong, Chan Lok-kwun, a troubled young man and mainland refugee, fights to survive within the notorious Kowloon Walled City. To make ends meet, he becomes involved in underground fighting rings. When he is betrayed by the crime lord Mr. Big during an attempt to purchase a fake ID, Chan steals drugs from him and escapes to the Walled City. There, he encounters Cyclone, a powerful yet caring crime boss who rules with a firm but protective hand.