Choi Renee just started her career as a detective for the Korean National Police Agency. She has everything in the palm of her hands, and is ready to excel whatever case she stumbles upon. The members of her weapons team were nothing normal. In fact, they were the opposite of sane. They were nocturnal human beings who worked the night and slept mere hours of day. The distracting face of Kim Seokjin, the sisterly attitude of Ahn Hani, unusual quirkiness of Lee Taemin, and the occasional iness of Oh Sehun were more than what she bargained for. Their team leader was on of a kind, too. Mr. Zhang Yixing was known to be the wise turtle of the whole detective intelligence department. Together, they all were capable of any case or disaster. But quickly things escalates for the worst and she is exposed to the horrors of the underground world. No training and exams could prepare her for the situations she would step upon. She is barely coping up, trying her best to build up barriers to separate her personal life from her professional life, but it all crashes to an end when she realizes. She is drowning and no one can save her.