One of the best travel writers now at work in the English language brings back the sights and sounds from a dozen different frontiers. A cryptic encounter in the perfumed darkness of Bali; a tour of a Bolivian prison, conducted by an enterprising inmate; a nightmarish taxi ride across southern Yemen, where the men with guns may be customs inspectors or revolutionaries-these are just three of the stops on Pico Iyer's latest itinerary. But the true...