As the daughter of a prominent judge of Khazaria, twelve-year-old Ziva is expected to focus on learning etiquette and decorum in hopes of finding a good husband. But she doesn't care about any of that. Instead, she spends her days with her twin brother, Pesah, as they work to try to find a cure for his leprosy. Now Pesah's getting worse. The best doctors have given him mere weeks to live, and even more alarming, Pesah has a vision: the Angel of Death is coming to collect him on Rosh Hashanah, only one month away. In a panic, Ziva runs away with Pesah to the Byzantine Empire, home to hundreds of doctors. Surely one of them must have a cure. But when Ziva accidentally frees a half-demon boy named Almas on their journey, unintentionally binding him to her until his debt is paid, Almas tells her about the legendary city of Luz, where the Angel of Death is forbidden to tread. If the three of them can get there by Rosh Hashanah, they can cure Pesah for good. They just need to run faster than the Angel of Death can fly...