Sam Gayton 
His Royal Whiskers [EPUB ebook] 

A young alchemist and a giant cat stage a meow-tiny to take down an evil czar in this charming Carnegie Medalnominated middle grade adventure.Something bad has happened to Prince Alexander, the only heir to the mighty Petrossian Empire. Something worse than kidnapping. Something worse than murder. Somehow, the Prince has been miraculously transformed into a fluffy kittenand a large one, at that. Giant, in fact. Dinosaur-sized. And his father, the bloodthirsty czar, is not happy. Why has this terrible catastrophe happened? Who are the boy and girl brewing secret potions down in the palace kitchens? And how are they paws-sibly going to avoid getting their heads chopped off?