Actor LeeByeng-hun, KimTae-hee, ChoiSeung-hyun, Kim So-yeon, Jeong Jun ho, KimSeung-woo

Introduction: "Best friends who are like brothers Kim Hyun-jun (Lee Byung-hun) and Jin Sa-woo (Jung Joon-ho), were training under the South Korean army's 707th Special Mission Battalion until they were scouted by NSS (National Security Service). The duo was independently scouted by the beautiful NSS agent, Choi Seung-hee (Kim Tae-hee). Unaware they have been scouted, the two were secretly captured and subjected through a simulated torture test, and both passed their test to be worthy NSS agents. In the process, they also fell in love with Seung-hee, who has kept the scouting process a secret from them. After completing the test, Hyun-jun and Sa-woo were introduced to the director of the NSS, Baek San (Kim Yeong-cheol). Baek San explained to them that the NSS is a secret organization tasked with preempting foreign threats and protecting the country's interests through wetwork operations, including assassination of anyone who could be a threat to South Korean (SK) national security. Since its founding in 1976, during the rule of Park Chung-hee, the agency's very existence has remained a state secret from everyone, including the President."