First, water freezes. Second, fuel freezes. By third the sky is jammed. Fourth and the mountains are saying it: time, time to go.

Up in the furthest reaches of the Indian Himalaya, where land touches sky, snakes the Manali-Leh Highway: the highest-altitude long road in the world, comprised of 475 kilometres, five mountain passes and more hazards than you have fingers to count them with. Traced on the thickest tectonic crust found anywhere on the planet, the route is as dangerous as it is sublime.

Simar Preet Kaur is in love with the mountains. But her picture of the landscape is incomplete. Armed with nothing but a rucksack and a notebook, she sets out on a thirteen-year quest in pursuit of the legendary truckers who know it better than anyone else. These are the 'ustads', the maestros, daredevil kings of the road who brush their teeth with battery acid and swig diesel before they get to chai, known by their numberplates not their names. Perhaps they can help Simar tell the real story of the 'Sky Road'. Yet stopping them is hard and earning their trust even harder - until she meets 0425, the wiliest ustad of all.

Drawing on hundreds of journeys, thousands of interviews and countless near-death experiences, the result is a polyphonic portrait of an extreme place and the men who, for five months of the year, call it home. Sky Road is a raucous celebration of life lived with chutzpah in the most precarious of circumstances. For mountain truck drivers follow a work philosophy that flouts old wisdom: they load all their eggs in one basket and run with it.