To avoid the Korean War for the second time, the NSS is set up because of national security on the Korea peninsula. The members of NSS aret rained to become experts, they use any way to complete their task. They officially do not exist and is not recognized or protected by the government. Hyun Jun (Lee Byung Hun) and Sa-woo (Jung Jun Ho) are best friend and rival in the special forces 707. They are recruited into NSS. In a world of conspiracy and betrayal, they are in love with Seung Hee (Kim Tae Hee), who is a beautiful girl, also is a psychologist in the NSS.