Fantasiburg is the secret city of all fantastic creatures: here dragons, unicorns, mummies, werewolves and mermaids all live peacefully together. And they get along fine when humans don't stick their noses in. That's the way it was for centuries, until a misunderstanding brings the Rodríguez Rodríguez family to the city. Tania is a fantasy stories friki. Gon is used to being the most popular student in the class. But neither of them is prepared for life in a fantastic city. The appearance of a strange pandemic turns the city topsy-turvy. The unicorns let out rainbow coloured farts, levitate at midnight and their coats have turned fluorescent. When the inhabitants of Fanasiburg discover that the Rodríguez Rodríguezes aren't vampires but humans they blame them for the plague. Tania and Gon have twenty-four hours to find a cure and save the city… and above all, to stay in Fantasiburg.