Forest still covers 70 percent of Bhutan, a spectacularly mountainous country about the size of Switzerland with less than a million inhabitants, most of whom live in its fertile valleys. Upland, tigers, leopards and bears still wander the rugged slopes and so does, according to legend, the migoi, which is what the Bhutanese call the yeti. For the members of a British-American expedition, seeking the migoi is a way to get beneath the surface of an intriguing culture in which the virtual and the real happily coexist. Tradition shapes everyday life in the "Land of the Thunder Dragon," and Westerners who ignore that fact run the risk of mistaking science and reason for truth. By the time the expedition has completed its arduous trek, even the most skeptical members have long since concluded that anything is possible in such a vast, unexplored land so rich in wilderness and demonseven the yeti.