The story began around the same time as Iris, when Kim Hyun-jun is being hunted by the North Koreans as a traitor while in Budapest. South Korea President Cho Myung-ho (Lee Jung-gil) expressed interest in advancing nuclear technology to lead the world with the energy source most advanced and cost effective this century. To do this, he asked the black-ops agent Dr. Kwon Yong-kwan (Yoo Dong-geun) to help take defecting North Korean scientist, Dr. Kim Myeong-guk. Dr. Kwon received the mission, but it was almost destroyed by the Athens team, led by Son Hyeok (Cha Seung-won) for trying to steal Dr. Kim's nuclear technology. Romance agents Hye-in to the agency Jung-woo to balance between the orders of Athens and keeping alive Jung-woo. After Athens affiliate Son Hyeok was revealed, he was arrested by the NTS for questioning. However, the agent Athens recovered her and she now plans to kill President Cho. During this time, Jung-woo knows Hye-in is an agent for Athens, but because of his love, he allowed him to escape NTS.