Throughout the film, Chae Yi-do’s investigation closes in on Kim Gwang-il after discovering forensic evidence tying his luxury compound and vehicle to abducted and mutilated women across Gyeonggi province. However, whenever Yi-do secures an arrest warrant or corners Gwang-il, NIS agent Park Jae-hyuk steps in with legal injunctions. Gwang-il is placed under protective NIS/CIA custody under the pretext of voluntary defection debriefing.
The geopolitical motive is revealed: Gwang-il possesses the master access codes to his late father's foreign bank accounts, containing millions of dollars in regime slush funds. CIA operative Paul Gray demands those codes at all costs, making Gwang-il untouchable. North Korean operative Ri Dae-bum ambushes the convoy and abducts Gwang-il. However, Gwang-il's remaining network and shifting loyalties lead to a bloody firefight. Dae-bum is killed, and Chae Yi-do is shot point-blank in the head/face by Gwang-il, who smirks and taunts the dying detective.
Gwang-il is whisked away by the CIA to safety abroad. Park Jae-hyuk, witnessing the slaughter of Korean police officers and sickened by the realization that his agency has protected a psychopathic murderer purely for American intelligence kickbacks, snaps.
The Epilogue / Ending: The film jumps forward in time to Hong Kong. Gwang-il has resumed his comfortable, aristocratic life of luxury and violence under CIA protection. Jae-hyuk, now acting as an off-grid vigilante, tracks Gwang-il to his yacht/safehouse and violently slaughters Gwang-il’s armed entourage. He confronts Gwang-il directly, shoots him, and severs his head. In the final scene, Jae-hyuk meets CIA handler Paul Gray in an upscale café, drops the blood-soaked duffel bag containing Gwang-il's severed head onto the table, and leaves a stunned Gray behind—having finally closed the case not through law, but through decapitation.