A murder case, like no other, stumbles onto Jin Jung's desk. As he starts to investigate it, he finds something peculiar about it. Defying all boundaries as a prosecutor, he pushes forward with the case. However, public outrage and pressure from the higher-ups bring it to an abrupt stop.

Jin Jung has District Head Prosecutor Kim Tae-ho right where he wants him and gets the upper hand. However, to make sure he has everything to prove it in court, Jin Jung goes after the medical examiner who fabricated the autopsy report. Meanwhile, District Head Kim knows Jin Jung's plan and orders Prosecutor Oh to stop it from happening.

Jin Jung gets demoted to the Civil Affairs Division, also known as the garbage disposal office, where he meets Park Jae-kyung, a prosecutor who is as bad as Jin Jung back in his days. While Jin Jung deals with the civil complaint cases, he finds a lead in the Seocho-dong murder case. He joins forces with Shin Ah-ra to take on the man behind it all.

Jin Jung doesn't let up and pursues Deputy Chief Prosecutor Lee in the murder case. He goes to extremes and discloses evidence at Deputy Chief Prosecutor's inauguration ceremony, halting his promotion and making him the prime suspect in the murder. However, Jin Jung needs more solid proof and goes after it in the only way he knows how to get things done.

The death of Deputy Chief Prosecutor Lee Jang-won has Jin Jung stunned. All evidence points to his death as a homicide, but he's the only one who thinks that. Ditching all duties at the Civil Affairs Division, Jin Jung looks for hard evidence that could overturn Chief Prosecutor Lee's death as suicide.

Kim Tae-ho becomes the new head district prosecutor. The first thing he does is arrest Prosecutor Jin for the murder of Deputy Chief Lee. However, it's a little difficult for them to keep him detained. Jin Jung runs out as a fugitive and tries to clear his name.

Ah-ra discovers Jin Jung wounded and rushes him to Jae-kyung's house for help. Luckily, Jin Jung recovers without needing to go to the hospital. Jin Jung and his team focus on Prosecutor Oh for leads, while Ah-ra finds something in the client list that raises concern.

Jin Jung puts District Head Prosecutor Kim Tae-ho behind bars. However, he still doesn't know who is behind it all. He goes after Tae Hyung-wook, the chief secretary at Law Firm Kangsan, who he thinks killed Deputy Chief Lee. Meanwhile, Prosecutor Oh looks for help from Seo Hyun-kyu.

Jin Jung arrests Tae Hyung-wook, but she won't talk. Meanwhile, Prosecutor Oh joins Seo Hyun-kyu and gets sent to keep her mouth shut as her lawyer. Jin Jung thinks everything happening now stems from the murder of Park Ye-young and begins to focus on Kim Hyo-jun, the deliveryman who confessed to the murder.

Jin Jung learns about the past from Jae-kyung and realizes Seo Hyun-kyu had something to do with his father's death. Although Jae-kyung urges Jin Jung to let go of the case, Jin Jung vows to put Seo Hyun-kyu away for good. Meanwhile, Jin Jung remembers the MP3 player was his father's and attempts to unlock the files.

Park Jae-kyung's death destroys Jin Jung. He knows Seo Hyun-kyu was behind Park Jae-kyung's death and goes after him. After finding evidence linking Seo Hyun-kyu to the murder, Jin Jung visits Kim Tae-ho for help. Help that will put Seo Hyun-kyu away for good.

With the help of Oh Do-hwan, Jin Jung gets the evidence he needs and puts Seo Hyun-kyu on the stand. However, as Jin Jung attacks him with questions, Seo Hyun-kyu isn't worried. Meanwhile, Jin Jung brings in a witness that shocks everyone, including Seo Hyun-kyu.