The year is 1930 and the British are in Arabia. Ivor Willoughby, a young orientalist, embarks on an ambitious quest to find his father, an officer abroad with the British Army. In all Ivor's life, Robert has returned to England only once, bedraggled and wild-eyed with tales of As'ir, a land of sheikhs and white-turbaned bandits, where he is fighting alongside Captain Lawrence and is known by the name Ullobi. After that single meeting, Robert is never heard from again. Ten years on, Ivor must find out what became of him. So he sets out on the journey of a lifetime. Traveling to Cairo to join the Locust Bureau, then circuitously to Abha, Yemen, and along the Red Sea coast, Ivor searches everywhere for clues about Ullobi, but no one appears to remember him. Or perhaps they are afraid to admit to it. Along the way Ivor hears whispers of a woman warrior called Na'ema who was once a slave. Her story seems tantalizingly connected with his father's, and Ivor finds himself in the misty heights of Ayinah looking for an Abyssinian seer who was carried on the same slave ship as Na'ema in 1914 and might unlock the mystery.