Saving the world’s knowledge from destruction depends on the worst mule in history. The Caliphate of Al-Andalus, Spain, 976. The Caliphate has been blessed with a period of peace, culture, and science for nearly sixty years. The Caliph Abd al-Rahman III and his son al-Hakam II made Cordoba the Western capital of learning. But al-Hakam II dies young, and his son is only eleven years old. One of his viziers, Amir, seizes the opportunity to take power. Radical clergymen, in exchange for their support of the illegitimate pretender, want to see the 400,000 books in Cordoba’s library burn. The night before the biggest bonfire ever, the head librarian, a eunuch named Tarid, gathers all the books he can and loads them onto the back of a passing mule. He takes off in hopes of saving what he can of universal knowledge. Joined by a young copyist and a former apprentice who went on to become a thief and vagabond, Tarid and his lazy, over-burdened “bibliomule” set out on a madcap adventure: crossing nearly all of Spain with Berber mercenaries in hot pursuit.