To solve an undercover case pending for many years, the old police chief Situ Qiang sends police officer Huo Tao, who is desperate to raise funds for his daughter's medical treatment, to go undercover in a criminal gang. Huo Tao pretends to be a pickpocket and gains the trust of the gang leader, Lord Bei, and gets acquainted with a young pickpocket named Xiaofei. Cooperating with the police's plan, he discovers Lord Bei's collusion with others to steal business secrets. Finally, all the criminals are brought to justice, fulfilling Situ Qiang's wish.