A thrilling new novel exploring how memory shapes the soul, by "an astonishing storyteller" ( Financial Times ) Software prodigy Josie Ashkenazi has invented a program that records everything its users do. When an Egyptian library invites her to visit as a consultant, her jealous sister Judith persuades her to go. But in Egypt's postrevolutionary chaos, Josie is kidnapped—leaving Judith free to usurp her sister's life, including her husband and daughter, while Josie's talent for preserving memories becomes her only hope of escape. A century earlier, Solomon Schechter, a Cambridge professor, hunts for a medieval archive hidden in a Cairo synagogue. What he finds will reveal the power and danger of the world Josie's work brings into being—a world where nothing is ever forgotten. Interweaving stories from Genesis, medieval philosophy, and the digital frontier, A Guide for the Perplexed is a spellbinding tale sure to bring a vast new readership to the acclaimed work of Dara Horn.