City of Ember

A self supporting, totally enclosed city where there isn't any crime and everyone gets along sounds like it might be an easy life.
But 12 year olds, Lina and Doon, start recognizing that not only are food and supplies in short order, but the mayor appears to be in on a small group of people who are hoarding supplies. In addition to this injustice, they realize that the city's generator is closer to total and complete failure than the city authorities make it out to be.
Lina discovers a note that appears to be instructions for escaping the city, and with security hot on their heels, Lina and Doon make a run for the boats down in the Pipeworks.
City of Ember is action packed and filled with interesting descriptions of the city and how it operates. This would be a great book to recommend to young teens...both boys and girls.