" Secretly, Greatly " (은밀하게 위대하게) is a 2013 South Korean hit film that masterfully blends action, comedy, and intense drama. Based on the popular 2010 webtoon Covertness by Hun, it tells the story of elite North Korean spies living undercover in a small South Korean village.

: A young agent who infiltrates a local high school . He looks up to Ryu-hwan as his hero and mentor.

: The unit's top lieutenant who disguises himself as Bang Dong-gu , the village idiot. He perfectly executes his "fool" persona by falling down stairs daily and acting mentally challenged, all while secretly being a lethal combatant.

: An agent posing as a rock star trainee, despite having no actual musical talent.

The story follows three highly trained agents from the North's elite "5446 Corps" who are sent to the South to await reunification orders while posing as ordinary residents.