Eleven years after the canal ran dry, a litre of water in Jaisalmer costs more than a day's wages. The city lives on ration lines and six litres a head. The men who sell the rest do not want the rain to come back.

Seventeen-year-old Tarini Sodha can hear water moving under the sand. Her dying grandfather presses a strip of knotted cloth into her hands, nine knots, nine days, and tells her never to say where it leads.

With a half-broken caravan, a healer and her restless son, and a stranger who knows too much about what lies under the Thar, Tarini sets out for the one place the desert still guards. Behind her, the most powerful man in the district has already sent for his jeeps.

Some wells are lost. Some are hidden on purpose.