Her determination never falters: blocked by Indian and Chinese bureaucracy, she makes a 4,000 kilometre loop to the nearest legal crossing point into Tibet. When she rejoins the river she sees only caked earth, an abandoned boot and a bicycle tyre. The Chinese have cut off the water to meet their own requirements for hydro-electricity and irrigation. The concrete dam ‘looms up from the river-bed like a vast wave frozen in mid-air. I stare at it in disbelief, fighting back tears.’

The source itself still lies ahead in the mountains and she persuades a smelly, drunken Tibetan to be her reluctant guide. Whipped by sudden snows, wrapped in plastic sheeting against torrential rain, she sets off. But there is no sense of triumph: throughout we have heard the warning note. By the end it is a lamentation:

The river is slipping away through our fingers, dammed to disappearance … One day, when there is nothing but dry riverbeds and dust, when this ancient name has been rendered obsolete, then the songs humans sing will be dirges of bitterness and regret.

Blackwell Bookshop

Purchase your copy here, 10% off RRP