Sixteen year old Felicity lives in a world where the Dark rules. Humanity stays to the Wellsprings, illuminated swathes of land where the light of eternal fountains keeps the skies bright all day long. But beyond that, the world is wrapped in eternal shadows, filled with monstrous Horrors who pray on the unsuspecting. When Felicity discovers that she is a Turnkey, a guardian selected to protect the Wellsprings, her fate soon takes her deep into the Dark, where with the help of a mysterious boy named Tobin she must survive astonishing odds.