The Harmony Stone has been stolen from the Crystal Castle, and without it the Kingdom of Fantasy is vulnerable to an ancient enemy, The Invisible Army; Geronimo, together with Queen Blossom's daughter, Winglet, embarks on a mission to find the ancient crown which will defeat the Invisible Army and restore harmony to the empire--but they must make it back to the Crystal Castle before it is overwhelmed by the enemy.
| ISBN: | 9781338655018 |
| Publication date: | 1st September 2020 |
| Author: | Geronimo Stilton |
| Illustrator: | Danilo Barozzi, Silvia Bigolin, Carla Bebernardi, |
| Publisher: | Scholastic, Inc. |
| Format: | Hardback |
| Pagination: | 314 pages |
| Series: | Kingdom of Fantasy |
| Genres: |
Children's and Young Adult Fiction |