Secretly, Greatly 2013
Directed by Jang Cheol-soo | Starring: Kim Soo-hyun, Park Ki-woong, Lee Hyun-woo, Son Hyun-joo
Three elite North Korean sleeper agents live under cover for so long that they believe their cover stories are their real identities. They are shocked when they are ordered to kill one another or face death at the hands of an elite hit team.