A polar bear mother keeps watch over her cub as they wait for the coming winter and the plentiful feeding opportunities it brings. But there are threats abound: from cannibalistic male bears, to the devastating impact of climate change, which has delayed the seasonal freeze and put them at risk of starvation.
The final episode deals with the evolution of the most widespread and dominant species on Earth: humans. The story begins in Africa, where, some 10 million years ago, apes descended from the trees and ventured out into the open grasslands in search of food. They slowly adapted to the habitat and grew in size. Their acute sense of vision led to them standing erect to spot predators, leaving their hands free to bear weapons. In addition, the primitive apemen also had stones that were chipped into cutting tools. Slowly, they grew taller and more upright, and their stone implements became ever more elaborate.
The first episode introduces the viewers to the continent of Antarctica and the surrounding sea and islands, its glaciers and the icebergs that form from it. It describes how the continent changes throughout the seasons, as it effectively doubles in size in winter when the surrounding sea freezes over, "the greatest seasonal change that takes place on this planet".
Across our planet, there are a handful of places that truly astonish, like Mount Everest, the Grand Canyon and Victoria Falls. These wonders seem to have little in common other than - literally - taking your breath away. But they share one other thing: they pose extraordinary challenges for their inhabitants. The second of two documentaries profiling some of the world's most expansive - and inhospitable - landscapes, and the people who live there. A fisherman in Zambia faces off against crocodiles and risks being swept to his death as he tries to make a living above the imposing Victoria Falls, and in the Amazon, a giant fish offers salvation to a hungry family that calls the river home. A boy's future hangs on the outcome of a single horse race in the vast grasslands of the Steppe, and in a European salt marsh, a young man duels with a savage bull in a centuries-old battle of wills.