City in the Clouds is the fourth book in the children's fantasy series by Tony Abbott.
Uh-oh! Neal has a problem. He's turned into a bug-again. Eric and Julie hope someone in Droon can help. Princess Keeah thinks there might be a cure in the City in the Clouds. Too bad the friends have only one day before the city disappears!
Eric, Neal and Julie are on the school bus on their way home from school. Suddenly, trouble stirs when Neal begins to transform into a bug once again. The kids hurridley go to Eric's basement and enter the magical realm of Droon in hopes of finding a way to reverse the bug spell while Neal develop various bug characteristics. Unfortunatley, the Rainbow Stairs lead the three kids onto the wicked sorcerer, Lord Sparr's flying ship. They are soon discovered by Ninns, cruel and beastly servants of Sparr, captured, and brought to the evil sorcerer himself. Sparr orders the Ninns to toss the kids overboard when Khan, king of the Lumpies, purple pillow-like creatures, and princess of Droon, Princess Keeah, attacks the ship with a strange gun, dispelling it and releasing the kids from Sparr's captivity.
Keeah and Khan explain to the kids that they were on the way to meet Keeah's father, King Zello, when they sighted Sparr's flying ship. Keeah also explains that they were on their way to the Flying City of Ro. She also tells the kids that Ro is protected by a spell of invisibility and flies all around Droon. Keeah adds that Ro's spell of invisibility only lasts when Ro has a sufficent amount of magical diamonds to fuel the spell, so, thus, Ro lands every year for one day in the Kalahar Valley to collect magical diamonds. Khan adds that if Sparr gets hold of the diamonds, he would possess an invisible army of Ninns and the results on Droon from that would be catastrophic. The five of them, knowing that they have limited time to save Ro and the magical diamonds from Sparr's clutches, quickly reaches Ro with the help of Khan's skills and a friendly Groggle, a dragon-like creature.
Upon reaching Ro, the kids and Keeah decide to go to the Guardians, wise and ancient inhabitants of Ro, for guidance while Khan chooses to meet with Zello. The kids discover that the Guardians are actually dinosaur-like creatures, theropods and called Bodo and Vasa, and the Guardians tell them that they could simutaneously break the bug spell on Neal and solve an mystery about Keeah's long-lost mother, Queen Relna, if they go to the Tower of Memory, an ancient tower in the center of the Guardians's palace that records everything that occurs in Droon. Keeah uses magic to turn them all into Ninns to evade capture by Lord Sparr, and she and Eric goes to the Tower of Memory while Neal and Julie tries to help Bodo and Vasa avoid imprisonment from Sparr also. Eric and Keeah finds that everything that is happening in Droon is being recorded onto the Tower by an enchanted quill called Quill and finds out the way to reverse the bug spell. Keeah also discovers that her mother was put under a curse because of Sparr and she is currently in the form of a white falcon. Sparr also enters the Tower, reads something inscribed on the top and for reasons unknown, spares Eric's life. The kids reunite with each other and the Guardians lifts Neal's bug spell.
The kids meets up with Zello and Khan and together they escape Ro just before its spell of invisibility is cast once more. However, Sparr and his Ninns have finally acquired the magical diamonds. Just before Sparr departs from Ro, he mysteriously says that Eric will help him, which is why he has not yet destroyed him, creating another mystery and ending the story on an ominous note and a dark cliffhanger. As cold as...ice.