In this exciting conclusion to the City of Ember series, we see how the Emberites have been faring in the Sparks village and how life has been for them. As they struggle through winter, finding enough food and supplies for everyone proves especially difficult. When Lina buys an old, raggedy book with missing pages from a roamer for Doon, he feels that there is a mystery attached to it that applies to the people of Ember. This book convinces Doon and Lina that they must return to their abandoned city to solve the mystery and hopefully find help for their struggling community.
The Diamond of Darkhold was a very satisfying ending to the City of Ember series. I had missed Doon and Lina in the third Ember book, The Prophet of Yonwood, and so was very happy to see their story resurface in this fourth book. I enjoyed the adventure, the mystery, and the great resourcefulness of Lina and Doon. This book was a delight to read!