*Top forensic pathologist Kang Min-ho is on the verge of retirement, eager to spend time with his daughter who has just returned home after years abroad. But when the dismembered corpse of a young woman, identified as Oh Eun-ah, is found along a local river, he agrees to take on one last case and performs a disturbingly graphic autopsy on the victim.*
The prime suspect is environmental activist Lee Sung-ho, who openly admits his guilt to rookie detective Min Seo-young. Lee claims the murder was a calculated protest against a construction project that would divide the river, carving it into six parts—hence six body parts. Yet the investigation repeatedly confronts clues that contradict his confession. Then Lee reveals that his daughter has been kidnapped. He allows Kang to call her, and her voice is heard crying for help. Faced with a direct threat, Kang must choose between his professional ethics and his daughter's safety, and he tampers with the evidence so Lee can be released within three days, or else the little girl will die.
As Min delves into Lee’s backstory, it becomes clear that Kang’s past is tangled in a separate, painful case: three men allegedly raped Lee’s sister. Kang manipulated the evidence for money for his sick daughter, acting as if the sister’s sexual history showed the assault was not forced. Oh Eun-ah had been a witness in that earlier case, and the three defendants walked free, fueling Lee's hatred toward Kang. The reason for Oh Eun-ah’s involvement grows murkier, and the tension between truth and loyalty thickens.
With Lee released, Kang traces him to the address he had directed them to, while Min senses that the three defendants are dead and that Kang may be next. After a brutal confrontation in which Kang strikes at Lee in defense of his own broken sense of justice, Lee finally reveals his daughter’s whereabouts. When Kang, Lee, and Min arrive, they discover a devastating sight: his daughter is dead, but only her head and limbs remain among rose petals—the body believed to be Oh Eun-ah was actually his own daughter. Lee’s earlier cries were recorded by him, adding a cruel twist to the tragedy. Kang collapses, tormented by the truth he has been living with, and the film cuts back to the grisly autopsy he performed, where he had repeatedly dissected his daughter’s body and tampered with it, unaware of the horror he had caused.
Lee taunts Kang, reminding him that hatred is easy to create but forgiveness is hard to find. Min pleads with Kang not to kill Lee for the loss of his daughter, but Kang draws his weapon and shoots Lee. As police arrive, Kang turns the gun inward and shoots himself, a final surrender to guilt. The closing voiceover, delivered by Lee, posits that hate can be a powerful force but forgiveness remains a harder, more elusive truth.
