It all began at the Oyster Bar in Grand Central Station, New York, in 1961 - Two Princeton graduates - John Hopkins and Joe McPhillips - have returned from Peru. Loathe to return to a life of work, marriage and mortgages, they are tempted by a mysterious letter from Kenya. Hatching a plan to ride a motorbike across North Africa, they buy a sleek, white R50 BMW and paint her name - 'The White Nile' - on the fuel tank, in honour of the route they plan to follow. In limpid, elegant prose, Hopkins describes deadly salt deserts and fig-laden oases, disappeared travellers and the funerals of young Tunisians killed in the battle for independence. He conjures up the ghosts of ancient Rome in Leptis Magna and of Homer's Lotus Eaters in Djerba . They encounter armed vigilantes in the Tunisian desert and outrun Libyan border patrols, barely escaping with their lives. They climb the pyramids of Giza at dawn and ride the 'Desert Express' across the wastelands of the Nubian Desert, but their final adventure, at Sam Small's Impala Ranch, is perhaps the most surreal of all -