Zhan Yan investigates a case to learn that a small black cat is to blame. Zhan Yan then investigates a murder. When he goes back to question a witness, he encounters Duan Mu Cui who is there catching the demonic criminal. The criminal kills her lover and herself after he sees her turn into a monster. Zhan Yan takes Duan Mu Cui back with him to investigate the case. (Source: jindreame at MyDramaList)