The following version of the book was used to create this study guide: Sutherland, Tui, Wings of Fire Book 3; The Hidden Kingdom. Scholastic Press, New York, NY, 2013. Kindle AZW file.

The Hidden Kingdom, a fantasy novel, takes place in the imaginary country of Pyrrhia, a continent with seven tribes of dragons. The SandWing queen was killed almost two decades earlier, and her three daughters are still fighting for control of the country's throne. A NightWing dragon named Morrowseer issued a prophecy predicting that five specific dragonets would provide the way for the end of the war. A group called the Talons of Peace have tried to arrange the situation so they were in charge of the dragonets. The dragonets managed to escape the cave and have spent the past days in search of a place to belong while figuring out how they might fulfill the prophecy.

As this novel opens, the dragonets are headed toward the Rainforest in the hope that Glory's family will welcome them. The group includes a RainWing named Glory, a MudWing named Clay, a SeaWing named Tsunami, a SandWing named Sunny, and a NightWing named Starflight. They are traveling with an injured SeaWing named Webs. They have interacted with several other tribes to varying degrees. Glory is trying not to get her hopes up with regard to her family. When they encounter the first RainWings, the tribe members knock out Clay, Tsunami, Sunny, and Webs, transporting them into the heart of their home while Glory and Starflight insist they can fly on their own. In the middle of the afternoon, everything comes to a halt. All the RainWings retire to hammocks and platforms above the treetops where they have direct access to the sun. Glory realizes that sleeping in the sun feels wonderful, though it has a numbing effect that makes her groggy.

Most dragons consider RainWings inherently lazy and useless, and Glory soon discovers they are not driven to accomplish anything. Eggs are placed into a community nest and allowed to hatch. Everyone sees it as too much work to track family relationships or learn. Though they have jobs, few are interested in doing them well. None of the dragons are interested in being queen; so, several are taking turns. None of them want to put forth any effort. When a dragon named Mangrove reports that several RainWings are missing, the queen applauds Glory's determination to find them. The queen's applause is because the missing RainWings will keep the queen from hearing Mangrove's complaints.

The dragonets of destiny discover there are secret passages from the Rainforest – one leading to a region near the Ice Kingdom and another leading to an island inhabited by NightWings. In the Ice Kingdom, they meet one of the sisters vying for the Sand Kingdom throne and discover she is frivolous and not involved in the war on her behalf. Glory also discovers the NightWings are holding the missing RainWings as prisoners. She feels she can only get the RainWings to fight if she is the queen leading them, and she sets out to win the throne. Though she loses the contest, a venom test reveals that the previous queen and Glory are closely related, and she hands Glory the throne.

As the novel comes to an end, Glory plans to begin training fighters immediately to launch a rescue attempt. Meanwhile, Starflight has been captured by the NightWings. The alternate dragons of destiny watch as NightWings carry him away.