Software prodigy Josie Ashkenazi has invented an application 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 abducted-leaving Judith free to take over Josie's life at home, including her husband and daughter, while Josie's talent for preserving memories becomes a surprising test of her empathy and her only means of escape.

A century earlier, another traveler arrives in Egypt: Solomon Schechter, a Cambridge professor hunting for a medieval archive hidden in a Cairo synagogue. Both he and Josie are haunted by the work of the medieval philosopher Moses Maimonides, a doctor and rationalist who sought to reconcile faith and science, destiny and free will. But what Schechter finds, as he tracks down the remnants of a thousand-year-old community's once-vibrant life, will reveal the power and perils of what Josie's ingenious work brings into being: a world where nothing is ever forgotten.

An engrossing adventure that intertwines stories from Genesis, medieval philosophy, and the digital frontier, A Guide for the Perplexed is a novel of profound inner meaning and astonishing imagination.