In just a few short days, 3 "Killing Smile" cases is shocked the whole city. During the investigation, a young but clumsy detective of Police Department named Wang Bu-er issues a shocking statement: "This is a case of mass murder." He and the expert inspector Huang Feihong start a terrified and dramatic investigation. Huang Feihong is visually indecent and quite mundane but actually a super grandmaster, he always helps Wang Bu-er to overcome dangers.