Six years back, an enigmatic shooting incident occurred in Seoul, leading to Han-kyu Lee (played by Song Kang-Ho) being dismissed from his position at the National Intelligence Service. Fast forward six years, and Ji-won Song (portrayed by Kang Dong-Won), a former North Korean spy, is now active within the Seoul metropolitan region. As both men conceal their true identities and pursue their own agendas, tensions begin to rise once more…