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.
The episode begins in the South American rainforest whose rich variety of life forms is used to illustrate the sheer number of different species. Since many are dependent on others for food or means of reproduction, David Attenborough argues that they couldn't all have appeared at once. He sets out to discover which came first, and the reasons for such diversity. He starts by explaining the theories of Charles Darwin and the process of natural selection, using the giant tortoises of the Galapagos Islands (where Darwin voyaged on HMS Beagle) as an example. Fossils provide evidence of the earliest life, and Attenborough travels a vertical mile into the Grand Canyon in search of them.
How and why dogs have become such good working companions, including Midge, the world's first police Chihuahua, and Joey, a sheepdog from the Cotswolds. Mother-of-four Toni Curtis gives her remarkable account of the fateful day when she was swept out to sea off the north coast of Wales and how she owes her life to the Newfoundland dog that saved her life..