I Saw the Devil

In the South Korean revenge thriller "I Saw the Devil," Kim Soo-hyun, a NIS agent (played by Lee Byung-hun), is thrust into a nightmare when his pregnant fiancee is savagely murdered by Jang Kyung-chul (Choi Min-sik), a sadistic serial killer. Consumed by rage, Soo-hyun abandons his lawful pursuit of justice and embarks on a brutal quest for vengeance. He employs his skills to capture, torture, and release Kyung-chul repeatedly, pushing the boundaries of morality and transforming himself in the process.