The People of Sparks by Jeanne DuPrau (0-375-92824-3)
This is the sequel to The City of Ember, and it continues the story of the Emberites return to the surface world. Lina and Doon deal with new issues as the Emberites come to a settlement called Sparks that takes them in. But the Sparks villagers resent the newcomers and the Emberites resent the restrictions placed upon them.
As tensions escalate, we see the echoes from the war that originally sent the Emberites underground to survive. My one quibble with the book is that the parallels between the battle in Sparks and the previous war is too clearly drawn. It is not left to the reader to draw the obvious comparisons. I feel that if it was more delicately handled, it would have increased the power of the message.
Kids who enjoyed the first book will also like this one, seeing what happened to the characters after they found the surface.