The Chaos King by Laura Ruby.
This sequel to The Wall and the Wing is a great read all on its own, though readers will want to find out the details of the first book after reading this one. Georgie is the Richest Girl in the World, but she is learning that wealth doesn’t solve all of her problems. She is shunned and teased in her new school and her friendship with Bug is disintegrating. Georgie would feel all alone, but before she can dwell on it, she finds herself once again in the middle of an adventure where a giant octopus, a pen that can alter the world, and a chocolate-loving sloth feature prominently.
Ruby has managed to take the world we are familiar with and change it into something wondrous and amazing. The city library has secrets galore, some people can fly, and there are incredible creatures at every turn. The book is fast paced and fun. It is certainly an adventure worth embarking on, I guarantee you will never see cats or budgies in the same way again.
Recommended for fantasy lovers from age 10-12.
