In the floating city of Vespera, memories are currency and powerful families trade years of their lives for magic. Debt-ridden illusionist Nessa Quill plans to steal one enchanted memory from the secret Midnight Auction and disappear forever. Instead, she accidentally bids away her own heart—literally—to Rhydian Noct, the mysterious Keeper of Lost Hours. Until the debt is repaid, Nessa cannot love anyone except the man who legally owns her heart. But Rhydian does not want her affection. He needs her unusual magic to stop the moon from falling out of the sky, and someone inside Vespera is willing to erase entire bloodlines to make sure it does.