Sometime in the near future, the Korean peninsula attempts to reunify. The South Korean government, which needs enormous funds for the unification to succeed, develops a landmark new technology called the TWR. The TWR is a high speed nuclear reactor and other countries want the technology.
To prevent terror in the aftermath of the TWR breakthrough, the government establishes a new organization named NTS (National Anti-Terror Service). Jung-woo (Jung Woo-sung) is transferred to the NTS group from the NIS. He's excited about the transfer and hopes to live the life of a real agent, but then discovers his main responsibility is to watch North Korean defectors.
One day, Jung-woo is given the order to travel to Italy to track terrorists from North Korea. Jung-woo goes to Italy with Ki-soo (Kim Min-jong). Ki-soo is a former North Korean agent who has defected to South Korea. Ki-soo's specialty is information on the European region. Up until now, Ki-soo was one of the North Korean defectors that Jung-woo had to monitor.
While in Italy, Soo-young (Lee Bo-young), the daughter of the South Korean President Jo Myeong-ho (Lee Jeong-kil), is kidnapped by terrorists. To solve the case the Korean government sends additional NTS agents including Jae-hee (Lee Ji-ah) to Italy. The NTS agents are able to negotiate with the terrorists, but during their negotiations Hye-in (Soo-ae) suddenly appears. Jung-woo and the other agents are surprised. Hye-in works as a guide at the exhibition hall in the NIS building. Jung-woo has always held strong feelings towards Hye-in, but he has never expressed his feelings towards her. Following Hye-in, Son-hyuk (Cha Seung-won), the chief of the East Asia branch of Department of Homeland Security in the U.S., suddenly appears as well. The NTS agents are mystified by their appearance.
Jung-woo learns that there is a secret "solutions" group within the NTS whose sole responsibility is to solve problems that others agencies can not. More surprisingly, Hye-in is part of that group.
Other mysterious cases start to occur and Jung-woo's intuition leads him to believe that there is unfathomable conspiracy occurring to rearrange the power structure of the entire world. That conspiracy is led by Athena.
What is the real identity of Athena and what does Hye-in and Son-hyuk hide in their NTS "solutions" group?