Eun Dae Koo (Lee Seung Gi) is a rookie detective who has the IQ of 150 but uses his foul mouth and tough attitude to mask his painful family history. Fellow rookie Eo Soo Sun (Go Ah Ra) is the sole female among the new hires but won’t let anyone push her around, even Seo Pan Seok (Cha Seung Won), the team leader of the violent crimes unit. Can the young new officers prove their worth?