Armed only with college Arabic and restless curiosity, Adam Valen Levinson set out to "learn about the world 9/11 made us fear." From a base in globalized and sterilized Abu Dhabi, he sets out to lunch in Taliban territory in Afghanistan, travels under the watchful eye of Aleppo's secret police, risks shipwreck en route to Somalia, investigates Yazidi beliefs in a sacred cave, cliff-dives in Oman, celebrates New Year's Eve in Tahrir Square, and, at every turn, discovers a place that matches not at all with its reputation.

While politicians and media eagerly stoke the flames of...