"IRIS" tells a breathtaking story of spies, filled with fights, betrayal, and romance.
Kim Hyun-joon (played by Lee Byung-hun), a confidential agent of the National Security Service (NSS), is best friends with his colleague Chen Si-yu (played by Jung Joon-ho). However, both secretly fall in love with their superior Choi Sung-hee (played by Kim Tae-hee). Later on, Hyun-joon and Sung-hee develop a romantic relationship. One day, Hyun-joon accepts a secret mission. During the mission, due to Si-yu's betrayal, he gets into a direct conflict with North Korea's secret agents Jeong Yong (played by Kim Seung-woo) and Seon-hwa (played by Kim So-eun), resulting in him being shot. Hyun-joon survives thanks to a mysterious "voice", and through this experience, he learns about the existence of the secret organization "Iris".