But he does. This is the utmost agony, but he has chosen to accept it. The sense of humiliation encompasses his whole body. It is as though he is being purged by fire, or ice; as though he’s fighting for his life in freezing water, trying to keep moving, trying to keep breathing, letting his consciousness contract around the agony, refined by its pain, saying to himself, There is only this moment, all the rest is a story, and wishing he could believe it.

3: THE SECRET BOOKS

NOW OPEN YOUR EYES. Take a moment to adjust to your new surroundings. We’re standing on a bank of yellow scree that crunches underfoot and slopes downwards from an immense limestone ridge too sharp and steep for snow to adhere to. Miles below us, the stubble of barley fields carpets the valley floor. Prayer flags snap in the breeze, their colours unearthly bright. In every direction, snowy peaks loom above cliffs of striated rock, dwarfing everything we can see. We are never quite reconciled to their presence.

The geography here is mystifying and sudden: alien empires are incongruously collateral. This is the high desert crossroad of Asia: China, Nepal and Tibet beyond those mountains, British India behind us, the expanding territory of the Russian Empire lurking to the north and west.

A train of short-legged, barrel-chested ponies winds its way through the dusty rock, attended by men in umber, ochre, grey. The giddying thin air is hallucinatory. There are visions up here in these mountains. On the farther slopes of the dry valley, something is moving. The men dismount and wait. Nicolas unsheathes a telescope and points it at the distant dots. Traders? Herdsmen? Brigands? ‘We’ll hold here,’ he says. This is a better defensive position. In the folds of his thick overcoat he has a revolver. He breaks the top and counts six bullets in the chambers. This land is claimed by many governments, loyal to none.

‘Give the ponies something to eat,’ he says, in Pashto, to his guides.

While he waits for the strangers to draw near, he swigs from his canteen of water. The desiccating wind steals moisture from everything without detection. No one sweats in this dry air. Leather cracks and falls apart.

The lead rider in the party of strangers urges his pony up the last fifty yards of scree. He’s wearing a Chitrali hat, but distinctive European army boots. He shouts a booming greeting in badly accented Hindi and unwinds the patterned scarf from his head to reveal a wind-burned English face: fox-orange eyebrows, freckles, blue-green eyes. The voice is rough from shouting commands; the diction is a gentleman’s. ‘Captain Francis Younghusband, King’s Dragoon Guards.’