"Moon King" is a fantasy novel written by A. J. Jacobs. It follows the journey of a young boy named Liam who discovers a hidden world on the moon. As he explores this magical realm, he encounters various creatures and learns about the importance of friendship and bravery. The story is rich with themes of adventure and self-discovery. Liam must confront challenges and make difficult choices to save both the moon and his home. The narrative combines elements of mythology and imagination, making it an engaging read for young audiences.