Jung Eunji's world is turned upside down when her best friend, Byun Baekhyun, comes home covered in blood one night.  Coincidentally, Eunji meets Kim Kai-- a boy whose life-long dream is to be a private investigator. Together, Eunji and Kai race to find out the truth about Baekhyun, but not without the help of some serious disguises, a few choir nerds, and advanced level calculus.