Two years ago I travelled to Assam to write about an itinerant theatre company there. Its latest sensation was a play in Assamese entitled The Life and Death of Princess Diana. When my guide heard that I'd come from London, he shook his head in despair. 'We had another Englishman here recently,' he said woefully, 'and we were thinking he was very mad. You see, he was totally obsessed.' 'Obsessed with what?' 'Obsessed with finding a dog.' I didn't think much of it, as you often hear of animal-obsessed Englishmen wandering in remote foreign climes. But as I read Mark Shand's new book River Dog, the Englishman with a canine fixation made sense to me at last.

The story begins in legend, the legend of a mountain so sacred that it was shielded by nature from mankind. Remote and mysterious, lying on the desolate Tibetan plains, it was said to stand 84,000 leagues in height, and to be walled with crystal and gold, rubies and lapis lazuli.