For centuries, the residents of the underground City of Ember have flourished in an amazing world of glittering lights and quiet contentment. But when the City's massive power generator begins to fail, the streetlamps fade - along with the hopes of the townspeople. Now it will be up to two courageous teenagers to follow a trail of clues left by the ancient builders to find the way out of Ember before their world is plunged into complete darkness.

In the year 241, twelve-year-old Lina trades jobs on Assignment Day to be a Messenger to run to new places in her decaying but beloved city, perhaps even to glimpse Unknown Regions.