The City of Ember, Jeanne DuPrau, Yearling, 2003, 270 pp
I read this so I could see the movie (that review is next.) I wasn't expecting much but it is great. It reads like a mystery and is a sort of sci fi for 9-12 year old readers. (Has this author read Isaac Asimov? Probably.)
The two main characters, Lina Mayfleet and Doon Harrow, are well drawn 12 year olds who are graduating from school and being assigned jobs in their dark city. Ember never has daylight and is only lit by incandescent lights run by a failing generator.
In the way of children that age, each is aware of the decrepitude and decline in their city and has enough intelligence to know that something must be done. Together they brave a corrupt mayor, blackouts and losses while they piece together the story of Ember and try to find a way to escape.
Ember, a world where it is always night, is fully created without a lot of boring detail. The vocabulary is perfect for the target reader ages and the pace is non-stop. The story arc made even an old cynic like me shed a tear.