The Diamond of Darkhold
Jeanne DuPrau
 The story begins with the Builders discussing what the Emberites should do when they are released from the city. The chief builder decides they should give them a piece of their own technology, but it is not found by the citizens of Ember because the vault door is covered by trees. Nine months later Lina Mayfleet and Doon Harrow are curious when a roamer comes into town with a mysterious book. They trade the roamer a match for the book and discover it only contains eight pages. On the front of the book the words "For the People of Ember" are printed in gold letters. Since they can't make sense of the book, they decide to go back to Ember. When they return, a family of squatters has taken over the darkened city. The Troggs (Washton, Kanza, Minny, Yorick and an adopted boy called Scawgo, who are named after various American cities) believe they own Ember, and rename it Darkhold. They capture Doon while Lina goes back to Sparks for help. Meanwhile, Lizzie Bisco (from Ember), Torren Crane, and Kenny Parton (both from Sparks) realize that the two are gone, and decide to go and try to find them. They don't succeed and a search party goes to look for them. While Doon is with the family they show him a diamond they found just outside Ember. Doon steals the diamond and escapes from Ember with help from Scawgo. While escaping, he also breaks the pipe connecting the generator to a waterwheel that created power for Ember, therefore shutting down Ember's lights for good. He finds Lina, who is being attacked by a pack of wolves. Doon throws the diamond at the wolves to frighten them away but shatters it in the process. Lina treats his wound and takes Doon up to where the book with eight pages and the original diamond were discovered. They find a switch that uncovers shelves filled with hundreds of diamonds. Lina and Doon figure out that the diamonds are solar-powered sources of electricity. A lot of people decide to help them go back to Ember and look for other things to help in the winter. Doon thinks about going back to his old home and recover his book of bugs, but changes his mind, stating he can create a new one filled with the unique bugs in Sparks. Lina, however, looks for her drawings of her dream city at her old home but it isn't there. She then goes to City Hall and stands on top of the mayor's building and says "Goodbye Ember, forever." They bring back thousands of new inventions, which earns the town money and food to last the winter. A weary group of roamers, who are actually the Troggs, come into town one day, and the diamond is returned to them. But soon they learn the truth. There are hundreds (maybe thousands) of them and they can power all sorts of electronic devices as well as start fires. They also learned that Doon and many others lived in Ember before them, and that they left and evacuated because Ember was dying. So the Troggs come to live in Sparks as well. In the end, it is revealed that in the future, cities are rebuilt with the power of the diamonds and Lina, Doon, and Poppy all live together in a house in Sparks. It is revealed Lina and Doon are married,and have four kids named Mariana,Johnny, Pedro and Eliza. Lina gets a horse named Fleet and becomes a messenger between towns and Doon goes on to study the diamonds.