Due to an accident on a plane, a cold man with amazing unlocking skills caught the attention of female criminal police Qin Zuoman. In a strange closed room murder case, Qin Zuoman accidentally discovered that he was Mu Xia, a newly hired security expert from the Public Security University. As all kinds of closed room cases continue to emerge, the stubborn "young lady" Qin Zuoman, the sultry "tech geek" Mu Xia, and the off-line "Internet celebrity" policeman Tan You, this trio of happy enemies, face impossible challenges again and again, open the locked rooms one by one, and the locked truth is gradually revealed...