When Sydney Wignall set off on an illegal climbing expedition to the Himalayas in the 1950s he little thought that he would become involved in an extraordinary, life-threatening adventure which would involve both Indian and Chinese governments at the highest level. Betrayed by one of the many spies operating on the frontier, his group was captured, interned in appalling conditions, and interrogated. Only when 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. Abandoned at the foot of one of the highest passes in the Himalayas, a pass never before climbed in winter, starving, exhausted and physically broken, their journey back in atrocious conditions has become one of mountaineering's great epics.