Nathaniel Fludd is ten years old, and he doesn’t know what to do with a phoenix, has never looked after a basilisk and doesn’t know how to navigate using maps, but he has to learn all this, because now the boy is the only assistant to his cryptozoologist aunt. This long and incomprehensible word is used to describe those people who study magical animals. Together, Nat and Aunt Fila travel the world and save magical creatures in trouble. Nathaniel must urgently fly to a small island lost at sea to help the unicorn. Lately the animal has been acting extremely strange. The journey would not be dangerous and even pleasant if it were not for the insidious Ovadius Fludd, who is pursuing the boy in the hope of taking possession of the Book of Monsters. Nathaniel will not only have to keep the book safe and sound, help the unicorn, but also find out from Obadiah where his parents are. After all, he is the only one who holds the secret of their location...