Tantric Buddhism, with its complex and fascinating rites, rose to its highest levels on the trans-Himalayan Tibetan plateau, where it had flowered since the eighth century. But now the small kingdoms - Sikkim and Ladakh among them - where the teachings and miracles of the great lamas were revered have been gobbled up by bigger powers.

The story of that loss is a prelude to Barbara Crossette's richly evocative journey into the historical past and courageous present of Bhutan, where the Buddhist world can still be seen intact, peaceful, harmonious - and threatened.

We enter a landscape of frozen peaks, high windy flatlands, and deep verdant valleys where, until the 1960s, the Bhutanese lived a medieval existence - where temples and monasteries, monks and lamas, provided not only spiritual but legal and even medical sustenance.

We move through farmlands, villages, and towns whose clusters of painted ornamental buildings and wooden half-timberings might be illustrations for old fairy tales, where thanks to Bhutan's devoted rulers change has thus far been gradual; where the tolerance, good humor, generosity - and gorgeous ritual - of Himalayan Buddhism continues to shine through.

Into this setting creep the tensions, deep and destructive, that threaten to wound Bhutan despite its best efforts to ward off the outside world. We see how open borders and recent air links have led to high-stakes smuggling of temple treasures and gold, as well as the ravages of AIDS; how tourism is importing dollars, distance from village roots, and a new urban phenomenon - burglary.