Li Ming, a special commissioner from the central government, is assigned to go undercover in Chang'an. Keeping a low profile, he investigates the city's darkest corners. There, he witnesses thugs bullying an elderly fruit seller and extorting protection money, learns that factory owners are colluding with the underworld to withhold workers' wages and threaten those who demand their rights, and uncovers prostitution, drug trafficking, and other illegal activities behind the city's entertainment venues. By day, Li Ming poses as a laborer to infiltrate businesses tied to organized crime. By night, he tails suspicious people and gathers evidence. Just as he is ready to take crucial evidence back to the central government, the criminal forces notice him and send an assassin after him. But after a fierce fight, he manages to subdue the killer. With the evidence in hand, he sets off for home, and Chang'an is on the verge of a sweeping crackdown on organized crime and a new dawn of justice.
