Shin Yu-Jin, a clumsy friend with shaggy hair who only knew about studying, he, who was once foolish, changes 180 degrees and shakes Lee Kang Hee's heart. "I can't watch you with other guys pretending to be friends anymore", her fluttering first love that started like that, is ended during an unexpected accident, leaving Kang Hee with trauma. Eight years later, Kang Hee is a homocide detective. She's been on an undercover job for a week and meets a strange man in a hotel lounge on the job. A face and coupling that resembles Yu-Jin's, soon after, the two continue to get entangled due to an inevitability like a coincidence..