It all starts from the murder case from five years ago that Do Chang was in charge of.

The execution of death-row convict Lee Dae Chul nears as well as the evaluation for Do Chang’s promotion. Knowing that Lee Dae Chul has an alibi at the time of the murder, Do Chang needs to decide whether to save an innocent man or to submit to the authority. Meanwhile, Do Chang and Ji Hyuk are joined by Seo Gyeong at Dae Chul’s old workplace, and that’s when Seo Gyeong gets a phone call from Park Gun Ho, who seemed to sound very urgent.

Although Do Chang and Mr. So prepare for the retrial of Lee Dae Chul’s case, Do Chang still needs to persuade Dae Chul to follow his lead because he is reluctant to take part in it due to the possibility of harm that it may cause his daughter. Meanwhile, Do Chang finds himself caught in a dilemma that is inflicting harm to both the victims who lost their beloved partners and the ones who crossed the line for their greed.

It was already difficult enough for Do Chang and others to get a retrial approved. However, feeling desperate during the trial, Dae Chul falsely admits to his killing of Detective Jang Jin Soo. Meanwhile, Seo Gyeong receives a recording from an unknown sender of a conversation between Superintendent Moon and a prosecutor, which could act as solid evidence to prove Dae Chul’s innocence.

Do Chang gets reinstated and returns to Violent Crimes Unit Two after coming to an agreement with Superintendent Moon. The team then focuses on Park Gun Ho’s case and stumbles upon Jo Seong Dae’s bloodstain at the murder site. This leads to the revelation of Chief Nam's wrongdoing as well as a possible connection to Oh Jong Tae. Just before closing in on Jo Seong Dae, the team catches the sight of the one behind the corruption.