Undercover NIS agent Park Seonwu is disguised as a café owner in an affluent neighborhood to investigate a drug ring. When he stumbles upon a lead about a drug-fueled party, he infiltrates it under the guise of delivering coffee. However, a lapse in judgement leads him to the brink of disaster until a cafe regular Seo Yohan rescues him. As the heat of the moment escalates, Seonwu and Yohan find themselves entwined in an unexpected physical connection. Realizing that Yohan might have crucial information about the case, Seonwu seeks his help. Yohan, attracted to Seonwu, agrees on the condition that they become friends with benefits. Their unconventional relationship deepens, but as the investigation nears its end, Yohan abruptly cuts ties with Seonwu and seemingly dies in a car accident, leaving Seonwu heartbroken. Three years later, Seonwu, now hardened by his past, spots Yohan in footage from a new NIS sting—alive and well, under the alias "Yohan Romanov," a notorious Russian mafia member. Fueled by betrayal and unresolved trauma, Seonwu embarks on a mission to Russia, determined to confront the man who shattered his world.