No Mercy

At a local river, a dismembered corpse is found and identified as Oh Eun-ah. Kang Min-ho, a top forensic pathologist about to retire, agrees to perform one last autopsy. The grim discovery sets the investigation in motion and introduces the film's clinical, meticulous tone.

Kang carries out a graphic autopsy on Oh Eun-ah, detailing the brutal dismemberment. He records evidence and notes the gore, letting his methodical observations drive the forensic narrative. The autopsy foreshadows the ethical compromises that unfold later.

Lee Sung-ho, the primary suspect, confesses to rookie Min Seo-young, claiming the murder was part of his opposition to a river-destroying construction. He asserts guilt and explains his motive as political and environmental. The police are baffled because clues keep contradicting his confession.

Lee informs Kang that his daughter has been kidnapped and that Kang may contact her to hear her crying for help. Kang is forced to leverage his professional authority to address a personal threat, blurring ethics and duty. The ploy tightens the emotional stakes for Kang.

Kang is pressured to tamper with evidence to secure Lee's release within three days. He starts altering findings and manipulating the case, trading ethical lines for the chance to protect his daughter. The first cracks in his professional integrity appear as the deadline approaches.

Min uncovers Kang's earlier case involving three men accused of raping Lee's sister and reveals that Kang tampered with evidence to help his ailing daughter. He shows that the sister's reputation was manipulated and Oh Eun-ah was a witness, leading to the defendants' acquittal. The revelation exposes a pattern of corruption and personal compromise.

With enough tainted evidence, Lee is released and Kang follows him to his home. Min realizes the three defendants are dead and that Kang will be the next target. The pursuit tightens as the past sins close in on the present.

Kang viciously beats Lee about his daughter, and Lee reveals the location of the girl. The trio heads toward the building Lee directed them to, hoping to locate the child and end the threat. The violence and intimidation reach a fever pitch.

They arrive to find the daughter dead in a pile of rose petals, with only a head and limbs remaining. The real Oh Eun-ah turns out to be a different hostage, contradicting the initial discovery. Kang collapses in shock as the true nature of the autopsy and its manipulation becomes clear.

Flashbacks reveal the graphic autopsy and how Kang injected semen into Oh Eun-ah's body, all unknowingly misidentifying the victim. The revelation reframes the investigation, showing how his professional pride contributed to a personal tragedy. The audience sees the extent of Kang's deception and its deadly consequences.

Lee taunts Kang and proclaims that he will live with the same pain. Min begs Kang not to kill Lee, but Kang shoots him and, as the police arrive, shoots himself. The cycle of hate ends in tragedy for all involved, with forgiveness out of reach.

The film closes with a voiceover from Lee about how easy it is to hate and how hard it is to forgive. The narrator reframes the entire story as a meditation on guilt, vengeance, and the possibility of mercy. The final reflections linger on the costs of the characters' choices.