In a world where loyalty is a rare commodity, Aizen, a highly-ranked Korean government agent, faces betrayal at home when she discovers her CEO husband, Jinyoung, has been unfaithful. Determined to distract herself and reclaim her purpose, she takes on an S-Rank mission, codenamed "David," involving a dangerous syndicate in Moscow. Partnered with the enigmatic and aloof half-Korean, half-Russian agent Taeyang, Aizen navigates the treacherous underbelly of the city, where their contrasting personalities clash and spark an unexpected connection. As they delve deeper into the mission, the stakes rise, and their dynamic evolves into a thrilling blend of tension, sarcasm, and romance. With danger lurking at every corner, Aizen must not only confront external threats but also her growing feelings for the unpredictable Taeyang, all while navigating the complexities of trust and betrayal.