The movie "Insider" is a crime action film that exposes the corruption and malpractices in Korean society through the experiences of conservative newspaper commentators, congressmen, large corporate committee members, gangsters, intelligence police, documentary photographers, etc. Lee Byung-hun plays the role of An Sang-gu, who was originally a "hound" of the powerful who did all kinds of bad things, but after he became a useless person, he became a "political gangster" who went to war against the powerful for revenge. Cho Seung-woo plays the role of "Prosecutor Yu Changxun", a blocker of corrupt politicians in the prosecutors' organization who kicks people when he wants to and covers up crimes when he wants to. Lee Qiangxi, a commentator of the Capital Daily, played by Baek Yun-sik.