In the 1980s, the notorious "no man's land" of Kowloon Walled City was infested with gangsters and was fraught with danger. A distressed young man, Chen Luojun (played by Raymond Lam), accidentally entered the city while fleeing and was unexpectedly rescued by the "big shot" Tornado (played by Louis Koo), and a sincere brotherhood was formed. At the same time, the evil gangs who had coveted the walled city for a long time set off a series of fierce battles to seize the walled city, and a high-burning and bloody battle to defend the home walled city broke out! This film is adapted from Yu Er's original novel "Kowloon Walled City".