A young widowed police officer, Lee Sun-Ae, finds herself unwittingly entangled in the world of international espionage after a chance encounter with Han Yoo-Il, a mysterious & charming young billionaire. Around the same time, she also meets Kang-Jun, the new director of Criminal Investigation Department, who happens to be an old friend of her late husband. Kang-Jun, who secretly harbors feelings for Sun-Ae, opens an old case surrounding Sun-Ae's late husband's death, which leads him to uncover of a secret that involves political and economic power figures, including Han Yoo-Il.