Noted pathologist Professor Kang Min-ho is retiring to spend more time with his beloved daughter. But when a beautiful, young woman turns up mutilated, he is drawn into one last case. Working alongside sharp and pretty rookie detective Min Seo-young, the investigation soon points to Lee Seong-ho, a respected environmental activist. When Lee confesses, it seems the murder is solved; But the evidence just doesn't add up, police are baffled and Kang continues to seek clues. When his daughter is kidnapped in an extortion attempt, Kang is forced to tamper with evidence, provoking a deadly battle of wits between a desperate father and a cold-blooded murderer with a hidden agenda; But it's a twisting line between justice and vengeance.