There are riots during demonstrations against the buildings in a bird sanctuary. As a result, public opinion swings in favor of the company. Prosecutor Byun Jae-wook is convinced that the company hired gangsters who dressed as protesters and eventually attacked the police in order to cast a bad light on the protesters. Jae-wook uses brutal methods. There are complaints with his supervisor Jong-gil, who then withdraws the case from him. But Jae-wook goes on and interrogates a witness who dies in custody overnight. Jae-wook is charged with murder and sentenced to 15 years in prison.
Jae-wook has a tough time in prison at first, as some of the inmates were convicted on his cases. But over time, Jae-wook's knowledge as a successful public prosecutor can make friends among the police officers and inmates and expand his network through favors. He would like to reopen the case and plead innocent. The interrogated died of shortness of breath due to asthma. But Jae-wook is certain that he had the asthma spray in the interrogation room. However, the reprocessing is rejected.
The new inmate, Chi-won, arrives at the prison. During a television report about migratory birds in the canteen, he recited the same text that the interrogated person told Jae-wook at the time. Jae-wook is curious and wants to know where he got this text from. But Chi-won declines, he says he is interested in birds. Jae-wook offers to help with Chi-won's case and can give his lawyer a valuable tip, whereupon Chi-won will be acquitted at the next court hearing. He helps Jae-wook gather evidence that Woo Jong-gil is behind it all.