In "I Saw the Devil (2010)", a vengeful secret agent embarks on a relentless pursuit to track down a ruthless serial killer who has caused unimaginable pain and suffering. As the agent delves deeper into the dark and twisted world of the killer, a dangerous game of cat and mouse unfolds, blurring the lines between justice and vengeance. Tensions rise as the two adversaries engage in a deadly battle of wits and wills, each determined to emerge victorious. With intense action sequences, gripping suspense, and a chilling atmosphere, "I Saw the Devil" is a thrilling and suspenseful thriller that will keep viewers on the edge of their seats until the very end.