Choi Young-Jin (Kim Hee-Ae) is a female detective squad chief. She also raises her daughter Ha-Eun. At work, she deals with brutal crimes with her senior detective Park Jong-Ho (Kim Min-Jong) and squad members Min Do-Young (Lee Da-Hee), Han Jin-Woo (Son Ho-Jun), Jo Jae-Deok (Heo Jung-Do) and Lee Se-Won (Lee Gi-Kwang).
