Geronimo joins the effort to rescue Blossom, Queen of the Fairies, who has been kidnapped by the Queen of the Witches and taken to the Kingdom of Nightmares.
After receiving a mysterious message summoning him to a meeting, Geronimo Stilton finds himself back in the Kingdom of Fantasy, summoned by the Elves, who want him to travel to the Great Explanatorium to find an answer to the earthquakes that are threatening the Kingdom.