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. When Lina finds fragments of an ancient parchment, she and her friend, Doon, put the pieces together to discover a message that seems to be directions out of the city. Is there something beyond the endless darkness? It will take all of Lina and Doon's bravery and ingenuity to find out - before the lights go out on Ember forever!