The Diamond of Darkhold by Jeanne DuPrau, 2008

It’s been several months since Lina and Doon escaped the dying city of Ember and, along with the rest of their people, joined the town of Sparks. Now, struggling through the harsh winter aboveground, they find an unusual book. Torn up and missing most of its pages, it alludes to a mysterious device from before the Disaster, which they believe is still in Ember. Together, Lina and Doon must go back underground to retrieve what was lost and bring light to a dark world.
In the fourth Book of Ember, bestselling author Jeanne DuPrau juxtaposes yet another action-packed adventure with powerful themes about hope, learning, and the search for truth.
(293 pages)

Was Diamond of Darkhold as good as the first two books (here and here)? No. But I was surprised how much better Diamond was than that dreadful prequel, Prophet of Yonwood (my review here) - in fact, it was only slightly less compelling than The People of Sparks was. And when you're writing the third book set around the same post-apocalyptic community, things are bound to get a little redundant. DuPrau does her best to combat this, taking old settings and recasting them in a whole new light.

The personification is wonderful: everyone, even minor characters, have their own personalities that are unique enough that you can differentiate between them, but they don't fall into stereotypes. Besides the main characters Lina and Doon there are many minor characters both old and new who play important roles in the story, all of whom have various backstories that meld into the larger story. Sometimes those backstories are short, but then again sometimes real-life backstories are short, too.

I love Lina and Doon, and I really enjoyed seeing them again. Their character development hasn't come very far from the first book, but it's definitely noticeable that they are both braver, stronger, and confident than they were in Ember. Their friendship has grown so that they are not just allies, but best friends as well. I appreciated that DuPrau didn't take their relationship to the next level during the bulk of the book, and left information about their future for the last chapter. The romantic in me hates that we didn't get to see Lina and Doon as a couple, but the realist in me appreciates that. For one thing, they're only like fourteen in this book. For another, they were busy! It's so annoying in most dystopian books how the main characters focus more on their love interests than they do on their missions. In the Ember books, romance is the last thing from everyone's mind and that makes my realist side extremely happy.

If you loved the first two Ember books, and then I highly recommend you read this as well. It brings the story full circle, tying everything off with a great mixture of realism and optimism throughout. Please don;t begin the series here, though - the first two books are both outsanding, and set the stage for this final book in the series.