Secretly, Greatly

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.

• 
  Jang Cheol-soo
• 
  Jo Seok-hyun

• 
  Kim Soo-hyun
  Won Ryu-hwan / Bang Dong-gu
• 
  Park Ki-woong
  Lee Hae-rang
• 
  Lee Hyun-woo
  Lee Hae-jin
• 
  Son Hyun-joo
  Kim Tae-won
• 
  Park Hye-sook
  Sun-im
• 
  Ko Chang-seok
  Seo Sang-gu
• 
  Kim Sung-kyun
  Seo Soo-hyuk
• 
  Shin Jung-keun
  Mr. Park
• 
  Jang Kwang
  Ko
• 
  Hong Kyung-in
  Jo Doo-seok
• 
  Lee Chae-young
  Ran
• 
  Park Eun-bin
  Yoon Yoo-ran
• 
  Choi Woo-shik
  Yoon Yoo-joon
• 
  Goo Seung-hyun
  Hwang Chi-woong
• 
  Um Tae-goo
  Hwang Jae-oh
• 
  Kim Beop-rae
  NIS General Manager
• 
  Jo Yong jin
  Se-yoong
• 
  Jo Young-jin
  Kim Hui-gwan
• 
  Lee Yeon-kyung
  Chi-woong's Mother
• 
  Ko In-beom
  NIS