Marie Lu transports us from the city streets of (possibly) Germany to the Kingdom of Back, a place where things are upside down and seemingly created by the sister of the famed Mozart, who appears to be the main character. When Nannerl is frightened that she will be forgotten, a fae princeling appears and shows her the kingdom and asks for her help in regaining its throne in exchange for helping her. I was drawn in from the very first pages and the writing just paints a beautiful picture. This book is definitely going on my to be read pile.