Assassin Kim Hyun Joon and psychological analyst Choi Seung Hee are lovers as well as colleagues at secret intelligence organization, NSS. Due to a friend’s betrayal, they go through hell with the unlucky fate of continually loving each other but unable to say or do anything about it. Jin Sa Woo is a secret agent who was at the top of his class. However, since meeting Hyun Joon and Seung Hee, he struggles to obey orders. He and Hyun Joon are friends in work but foes in love, as both care for Seung Hee. (KP's note: I’m not sure if Sa Woo is the one that betrays them.)
The character played by T.O.P is an assassin for IRIS, a secret organization hidden the States. He has been assigned to kill Hyun Joon. Kim Sun Hwa is a North Korean security agent who follows her security team leader, Park Chul Yung, like a shadow. She is also ordered to chase after Hyun Joon, but falls in love with him after being discarded by her country. Sato Eriko is an agent for Japan’s Defence Intelligence Headquarters.
Other: The cast and crew will film in several different countries (Japan, U.S., China, Russia) with an astounding budget of approximately $15 million USD (based on March 17’s exchange rate). Source: kpculture.com