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.

Ember City is being plagued by loud growls in the night. Drake, Li, and Runa's search for the source of the noise leads them to a mountainside cave. What they find inside isn't a vicious beast but a great snoring cave dragon! Can the dragon friends solve the snore so the dragons of Ember City can finally get some sleep?