One night in the year 411/1021, the powerful ruler of the Fatimid empire, al-Hakim bi-Amr Allah, rode out of the southern gates of Cairo and was never seen again. Was the caliph murdered, or could he have decided to abandon his royal life, wandering off to live alone and anonymous? Whatever the truth, the fact was that al-Hakim had literally vanished into the desert. Yet al-Hakim, though shrouded in mystery, has never been forgotten. To the Druze,...