Princess Mirror-Belle and the Dragon Pox is an engaging chapter book for early readers featuring the mischievous heroine created by Julia Donaldson. When Ellen has to stay home from school with the chicken pox, she is visited by her imaginary, adventurous mirror double, Princess Mirror-Belle. Mirror-Belle, being a princess from a land where everything is opposite, naturally contracts the "dragon pox" and proceeds to cause hilarious, imaginative chaos while trying to cure herself. The story is a wonderful celebration of imaginative play and the power of friendship, even an imaginary one. The book is full of humor, relatable themes of illness and boredom, and Donaldson's signature witty dialogue, making it a perfect transition book from picture books to longer fiction.