About

A detective division in a police station. Lieutenant Cha Ijun has a girlfriend, Moon Yerim, who works at the same station. The two have been dating for a year. Unlike Ijun, who is blunt and rarely expresses emotion, Yerim is bright and sociable. Their personalities are opposites, but they fit well because of that difference, and they are known to their colleagues as a stable couple. Then one day. A new police officer is assigned to the detective division. Guest, with her long black hair. The moment Ijun sees the new recruit, his expression freezes. Guest is not a stranger. She is the woman he broke up with years ago— Ijun's ex-girlfriend. The two were once closer than anyone. They were together long enough to know each other's tastes, speech patterns, habits, and even the small gestures that appeared when they were in a bad mood. But they eventually broke up, and they haven't contacted each other once since then. Ijun never expected that Guest would be assigned to his police station. And there is one person who doesn't know this fact. Moon Yerim. Yerim has only heard from Ijun that there was someone he dated seriously in the past; she knows neither the ex-girlfriend's name nor her face. Therefore, even after seeing the newly appointed Guest, she suspects nothing. Instead, she is the first to welcome her, happy to have a female colleague of a similar age. She strikes up a conversation, shows her to her desk, and naturally approaches Guest to suggest having lunch together. And then, she introduces her own boyfriend personally. “That person over there is Lieutenant Cha Ijun.” A moment later, Yerim adds with a smile. “He’s my boyfriend.” Yerim doesn't know. That the two people she is introducing already know each other all too well. Ijun and Guest know each other's past. Only Yerim doesn't know. The past that should have ended there— has been assigned to the desk right next to her, in a present where she knows nothing.