The Diamond of Darkhold: The Fourth Book of Ember (Books of Ember)

Doon and Lina see the Sparks as their home now. However, the winter is tough and things are scarce for the citizens. Life in Ember in someways were easier. They decide to go back when Doon obtains a book through a roamer and finds it's for the citizens of Ember. However, this roamer tore out a good portion of the book to use as kindling. That doesn't stop the dynamic duo. They trek all the way back to Ember without thinking of the bad possibilities such as sqwaters. That would be the Troggs. Doon is captured and Lina manages to go undetected. Doon is smart enough to say, "Go away! Get Help!" Lina goes back into the caves and runs into the roamer who sold Doon the book. It turns out Maggs (the roamer) is the sister to Troggs and supplies his family food by literally dropping it down a hole.

In the meantime, back in city of Sparks, Kenny misses Doon so he goes to Lina's place to look for Doon. He's told Doon is not there. That makes Kenny realize Doon and Lina are really missing. Later he gets Lizzie and Torren to go on a journey trying to find Doon and Lina. Good intentions but they lack the stamina that the dynamic duo has.

Lina finally leaves Maggs (who graciously offers Lina shelter for the night) and goes towards to cave to retrace her steps to go back to Sparks. There she finds Doon escaped the Troggs with the help of Scago, Trogg's adopted slave, and they make it back to the city (met half way by the adults in a wagon).

The Emberittes and some Sparks citizens go to the cave where it leads to the underground city of Ember and get all they can and say a final goodbye after Doon had literally shut the generator down forever so he can drive Troggs out of his beloved but dying city. Scago hands Doon the Diamond that turns out to be a conductor of electricity.

Goodbye and farewell city of Ember.

I'm not sure why DuPrau chose to gradually lower the reading level of this series, but this book reads much more like a book for children than the first three in the series, even though the characters and subject matter remain on a young adult level.

Be that as it may, this is still quite a good book. In the third book, the people of Ember and the people of Sparks are just barely managing to live together harmoniously, but conditions have not improved over the hard winter. Food is scarce and tempers are running short. When Lina and Doon discover a book that describes something left behind for the people of Ember, they decide to go back to their city and try to find this mysterious item, as well as see what supplies may have been left behind when the people left.

What they discover allows DuPrau to end her series on a very hopeful note. She does not disguise the fact that life continues to be hard, but she makes it clear that by working together, the people of Ember and Sparks are able to come together and make a bright new future. As cheesy as that sounds, she writes it so well that you can't help but smile and feel hopeful yourself.