Five years ago, Gu Yu's most beloved childhood friend, Wu, suddenly disappeared. To find him, Gu Yu enters the dangerous world of ghouls, disguised as a "mockingbird," humans who have sold their souls for a chance to change their fate. To save her soul from getting eaten, Gu Yu tricks her way into becoming the personal attendant of none other than the prince of demons, Jiu Tao. Will Gu Yu be able to find Wu, or will she be stuck with this prickly prince forever?