Modern police drama "secret police" in order to show the struggle in the anti drug first Interpol life, singing the praises of their safety and to defend his undercover drug trafficking group as the theme of the drama "secret police" drug "heroin" also known as the No. four, by the famous film producer Li Tie and producer Liu Kai shot meticulously. The famous actor Wang Kuirong, Zhao Xiaorui, Ren Shan the strong strong alliance. The plot of the story as one falls, the fate of the characters striking one snag after another. Usually in the gangster film, black and white two "crimson PK" is a major bright spot, "secret police" also did not pass and added many new elements. The specially arranged actors to school experience, then, as captain Ren Shan led the young officers, went through a real martial arts training. It is understood, in order to reflect the reality, play fight scenes need actor "the real thing" exercise, to play more. In addition, framing, director of the group to the real one, old factories, old factory building, old equipment, old dormitory became shooting focus, this dusty field view, let the exciting a layer of the original whirling story printed on the mystery.