: Kim Hyeong-jun (Byung-hun Lee) and Jin Sa-woo (Jun-ho Jeong) are blood brothers who served together and swore to trust each other and unchanging friendship for life. One day they meet an enigmatic girl Choi Seung-hee and fall in love with her without saying each other a word. Surprisingly the girl appears to be a special security agent who was send to collect profiles before recruiting them for a top secret organization known as the National Security Service (NSS). Kim Hyeong-jun and Jin Sa-woo are both succefully passing the tests and joined NSS as a new security unit under Choi Seung-hee's supervision. Ignoring NSS rules Kim Hyun-jun and Seung-hee become close. Sa-woo fights to hide his feelings for Seung-hee and hopes for his friend's happiness.
One day, they are immediately sent on a mission to Hungary. When they successfully finish off their job with immaculate teamwork and are celebrating it, a message arrives to Hyun-jun asking him to meet in secret for solo mission. Things take a drastic turn then and he loses everything and discovers a secret society called 'IRIS'.
- The series was filmed around the world, including places where Korean dramas were never filmed before, such as Hungary.
- Boasting a budget of more than 20 billion won (US$17 million), starin best known A-list actors and produced by one of Korea's top production companies, Taewon Entertainment, 'IRIS' is aiming for a new chapter in Korean dramas.
- 'Iris' based on the hit movie Shiri (1998).
- A member of the hugely popular idol group Big Bang T.O.P - plays role of the IRIS assassin named Vick.