Secretly, Greatly (2013)

Cast: Kim Soo-hyun, Park Ki-woong, Lee Hyun-woo, Son Hyun-joo, Ko Chang-seok, Kim Sung-kyun, Shin Jung-keun, Hong Kyung-in, Lee Chae-young, Park Eun-bin

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…