A police detective who loses everything to a criminal organization seeks payback when he gains special abilities through biotechnology.

Chief of the ‘Special Crime Unit’, OH Gu-tak, looks for the former gangster, PARK Woong-chul, whom he had worked with before, and recruits a con artist, KWAK No-soon, and a convicted cop, KO Yoo-sung in the new team. With new blood, the ‘Bad Guys’ have become stronger and tougher. As they dig deeper into the case, they sense that a much bigger crime organization is behind it all and they begin the hunt for bad guys…

Son Ji Eun moves to a small city due to her husband's new job as a civil servant. She works part-time at a mart. Son Ji Eun is quiet and sincere. Her life in the small city becomes boring. Son Ji Eun's life is shaken by Yoon Jung Woo. Yoon Jung Woo is a biology teacher at a local school.

To combat rising violent crimes, the Police Chief asks Detective Oh Goo Tak to form a team consisting of criminals. He is currently suspended from the police force for using excessive force. He then gathers team members: Park Woong Chul who is a gangster, Lee Jung Moon who is the youngest serial killer with extraordinary intelligence and Jung Tae Soo who is a contract killer. Police Inspector Yoo Mi Young also joins the team and she tries to have these guys work as a team by dealing with them rationally and sometimes emotionally.