Ridiculed by the neighbourhood children Jimmy runs away to find a place where he fits in. He stumbles in the forest and falls into an underground world: Roombelow.
Jimmy rescues the town from the curse of the sleeping spell and is ‘adopted’ by Mr McDonald, the Mayor. Witch Matilda and Gemma, the little lady who lives at the bottom of the well, but doesn’t know how she got there, become Jimmy’s best friends.
When Roombelow is in danger of flooding, Jimmy locates the sleeping Weather Man and turns off the torrent.
Then the well in Roombelow dries up. Jimmy and Gemma find the cause and return the giant eel to the sea.
Jimmy visits Aunt Ethel who explains that Jimmy is an orphan from the starworld of Attalia. He could return to Atallia but chooses to stay in Roombelow.
After battling with Erg, the chief troll, Jimmy ends up in a cliff-side world where he discovers the Diamonites, who look very much like Gemma.
Gemma is taken back to meet her family but is kidnapped by the Traders. With the assistance of Witch Ira, Jimmy sets sail on a rescue. Gemma stays with her family while Jimmy returns to Roombelow.
Jimmy decides to visit his birthplace – star world Attalia. The starship automatically heads homeward. On the way, the ship is attacked and destroyed by enemy forces. The Attalian Rescuers pluck Jimmy to safety and he is befriended by Commander, Zaru. On Attalia, Jimmy has no relatives and becomes the guest of President Alpha.
Kursh attacks and there follows a war waged with missiles, lasers and force fields. The Attalian forces succeed in thwarting the onslaught.
Jimmy plans the destruction of the time warp to close the portal between Ock and Attalia. Once continued peace is assured, Jimmy decides to return to his family of friends in Roombelow.