Esau by Philip Kerr (Author)

Jack Furness, a world-famous mountaineer, is scaling one of the highest peaks in Nepal when he slips and falls into a crevasse. In the snow he finds a fragment of skull preserved in almost immaculate condition, and on returning home presents it to his ex-girlfriend, Dr. Stella Swift, a paleoanthropologist at Berkeley. Stella is intrigued. The skull, when she examines it, seems to be a rare example of an early hominid, a form of ape-man which science had yet to classify. She also discovers that the skull is not millions of years old, but alarmingly recent.
Stella and Jack set about organising a new expedition to the Himalayas, to rediscover more of the fossil material, and maybe even to track down a living example of this strange creature. But they have problems: there are threats of a nuclear war, and there is a narrow gap of time in which they can make their trip safety. And Jack becomes quickly aware that one member of their team may have a secret mission that may conflict with their own.
The story of expedition, and of what Stella and her team find there, make Esau one of the most heart-stoppingly exciting thrillers of recent years.