In 1995, a mathematics professor who is not yet tenured, Kim, exposes a flaw in the College Scholastic Ability Test, triggering the public humiliation of the professors who drafted it. A few years later, despite the quality of his research, he is denied tenure and forced to resign. He relocates to the United States for a time, but returns to South Korea after the laws are amended to allow rejected professors to file wrongful-dismissal lawsuits.
In 2007, with his case lost and his appeal dismissed, Kim decides to confront the appeals judge at the entrance of the judge's apartment. He brings his cross-bow, a hobby he keeps at a range, and a physical struggle ensues. Kim is arrested, and the judge—who initially appears uninjured—disappears from the scene and reappears minutes later with a minor puncture in the abdomen, after which he is taken to the hospital. An assault against a judge is a serious crime, and the case draws widespread attention.
Meanwhile, Park, a lawyer deeply in debt, is approached by Kim's wife to take the case, but she changes her mind when she learns that Park is an alcoholic. The trial proceeds with a different lawyer, and Kim pleads No Contest in response to what the trial judge seems to show as prejudice and dishonesty. Now in prison, Kim files for appeal and hires Park on the advice of Jang, a journalist. To Park's surprise, Kim has studied the law on his own and often argues about how to present the case. As the appeals hearings unfold, Kim repeatedly confronts the judge and prosecutor over signs of dishonesty, citing relevant laws and passages from the constitution they have allegedly violated. With Park and Jang's assistance, he points out several holes in the prosecutor's evidence and in the victim's testimony.
The appeals judge resigns and is replaced by another who does everything possible to obstruct the proceedings and protect the prosecutor, even though it becomes clear that Kim never shot the victim. In fact, the victim stabbed himself minutes after Kim's arrest, and his family later procured the blood-stained clothes after he was taken to the hospital. The absence of the arrow that punctured the victim remains unexplained, fueling public unrest: some citizens riot and protest Kim's innocence, while a judges' association demands the opposite verdict. Park, losing hope, contemplates pouring water on the appeal judge as a form of protest, but Jang confiscates the water bottles. Around this time, Kim is raped during the night by another male inmate.
Although the appeal is denied, Kim receives a more lenient sentence of four years instead of ten. While in prison, he continues to cite the law and argue with the guards, and upon his release he becomes a lifelong activist for judicial transparency. This arc traces how a single legal fight expands into a broader struggle for accountability within the country's courts, and how one man’s persistence leaves a lasting imprint on a society watching its institutions with cautious scrutiny.
