When Sidney Wignall set off on a climbing expedition to the Himalayas in the 1950s, he little imagined he would become embroiled in an extraordinary, life-threatening adventure that would involve both Indian and Chinese governments at the highest level. In 1955, the Indian Nehru Government was desperate to keep on good terms with the new communist China and so ignored mounting evidence of a Chinese military build-up in Tibet. As Indian concerns grew, a number of Indian army officers devised a plan for an investigative climbing expedition to cross the frontier into Tibet. The risks were enormous. The brutal methods of the Chinese Government were well known and Tibet had only recently been conquered. Sidney Wignall agreed to help them. Betrayed by one of the many spies operating on the frontier, his group was captured, interned in appalling conditions, and interrogated by some of the most senior Chinese officers in Tibet. All the time, Sidney Wignall watched and noted. Finally, as international pressure grew, his group was released to walk through Nepal back to India. But the Chinese had no intention that they should get back alive. The group was abandoned at the foot of one of the highest passes in the Himalayas, a pass never before climbed in winter. Starving, exhausted, physically broken, their journey back in atrocious conditions is one of mountaineering's great epics.