Sook-hee is a trained assassin who was born to kill. She was just a little girl when the training started in Yanbian, China. After the death of her mentor, when the chance of starting a new life was given to her, she came to South Korea as a government agent. They promised her that she will be free after ten years of service. So she begins her new life as a theatre actress. But soon two men Joong-sang and Hyun-soo appear in her new life. And she started to find deep dark secrets about her past. Eventually she take matters into her own hands.
Jae-ho has established his own rules and put all of his fellow inmates under his control in a penitentiary facility. After he meets a newly imprisoned inmate, Hyeon-soo who won't give in to anyone under any circumstances, Jae-ho pursues his new ambition to become the boss of his organized crime group once he is released from the prison.
Hwang Ki Joon, Mr Action, and Kang Hee Yeol, Mr Bookworm, are two best friends but contradictory students at Korean National Police University. They accidentally witness a kidnapping and decide to work together to track it down.