A book that follows the story of reindeers and humans. Both arrived in Europe at roughly the same time. The reindeer took a winding route from South America, through North America and Beringia in far-eastern Russia, before crossing the Ural Mountains and beginning the journey southwestward into Europe. Humans, on the other hand, started in Africa and entered Europe from the south. One adapted to a life surrounded by snow and ice; the other was entirely dependent on the heat of the sun. A claim that such vastly different species would forge strong bonds and become mutually dependent would have seemed far-fetched. But that’s exactly what happened!For over 500,000 years, large herds of migrating reindeer sustained three different human species during the harshest climatic periods. Time and again, as cold and glaciers pushed humans into small ice-age refuges, it was reindeer that were consumed by the light of flickering fires. Today, a steadily warming planet and habitat loss threatens the survival of the reindeer. Now, it is the reindeer that needs help from humans. The time has come for a role reversal in the mountains.