Peering through the windswept snow on a dark February day, the rescue party finally came on the first sign of life — the flapping remains of a tent pitched on ski poles on an uppermost slope of Kholat Syakhl, ‘Mountain of the Dead’ in the native language of northern Siberia. But where were the nine young Russian students who should have been sheltering beneath the canvas? Curiosity turned to mystery as human tracks were seen in the snow heading downhill away from the tent in single file for a third of a mile... barefoot human tracks. In temperatures of minus...