Eun Dae Gu, Uh Soo Sun, Park Tae Il and Ji Gook – otherwise known as the P4 – are the new recruits in the violent crime unit at Gangnam Police Station. These rookies are neither enthusiastic, nor passionate about their new jobs and have joined the crime squad for varying but unbefitting reasons. They are lead by an erratic and hot headed Seo Pan Suk who wants nothing more than to wash his hands of the incompetent new recruits.