Being the famous suspense novel assistant is difficult, it's more difficult when the writer is an attractive, hot, single young man with lot of charms such as Kim Jongin. When Suzy finally agreed being Kai assistant she thought she would only deal with fanletters, handling fangirls and organizing Kai's schedule all day but she was wrong...

One day a highschool student found murdered tragically in a classroom. The victim chest was cut open by a knife and his heart were taken by the murderer. Kai and Suzy called by Seoul Police Department to answer some questions and help them solving the case because this case was described in one of Kai's novels.

All of us know that Suzy stole Kai's heart but this case is different thing. The victim heart were really ripped out from the body. The victim heart stolen by the murderer.

Once upon a crime...

There's a 'Classic Case' where the golden boy killed brutally

They must find the murderer

But what if the murderer find them first?