Light shines in the city of Ember-but at the city limits the light ends, and darkness takes over.  Out there in the Unknown Regions, the darkness goes on forever in all directions.  Ember-so its people believe-is the only light in a dark world. 

And now the lights are going out.

Is there a way to save the people of Ember?  No one knows.  But Lina Mayfleet has found a puzzling document, and Doon Harrow has made discoveries down in the Pipeworks.  With these clues they start their search.