The story is about a prosecutor who takes the law into his own hands. He will do anything to put an end to the greed of people who use their money and power to exploit others. He doesn’t care about standard procedures and resorts to unlawful means to stop corruption in society. Jin Jung (Doh Kyung Soo) is a prosecutor with a deep sense of justice. He always stands up for the weak and fights for them based on the principle of "an eye for an eye, a tooth for a tooth." He wants the victims to get revenge ten times greater than what they endured. Shin Ah Ra (Lee Se Hee) is a senior prosecutor in the Criminal Investigation Department of the Central District Prosecutor’s Office. With her methodical approach to organizing matters and her ability to assess situations objectively, Shin Ah Ra has become the office chief’s right-hand woman. Furthermore, Shin Ah Ra has a sixth sense when it comes to politics and remarkable social skills, which allow her to maintain good relationships with her peers, both senior and junior colleagues at work, as well as with senior prosecutors. Although she seems to be a completely different type of person from the eccentric Jin Jung, Shin Ah Ra will care for him and protect him more than anyone else.