Welcome to an extreme landscape of rock, ice and snow. We tour the mightiest mountain ranges, starting with the birth of a mountain at one of the lowest places on Earth and ending at the summit of Everest. Find out how some of the most secretive animals rise to the challenge of mountain life. Share one of Earth's rarest phenomena, a lava lake that has been erupting for over 100 years. The same forces built the Simian Mountains where we find troops of gelada baboons nearly a thousand strong. In the Rockies, grizzlies build winter dens inside avalanche-prone slopes and climb the peaks to devour abundant summer moths. In another world first, the programme brings us astounding images of a snow leopard hunting on the Pakistan peaks.
In this first episode they travel from July to the December solstice, experiencing spectacular weather and the largest tides on Earth. To show how the Earth's orbit affects our lives, Helen jumps out of an aeroplane and Kate briefly becomes the fastest driver on Earth.
The second episode of this unique scientific study reveals the wild side of pet cats. Using GPS trackers and cat cameras, they show how these felines transform from pampered pet to purring predator as soon as they leave the cat flap. Liz Bonnin and some of the world's top cat experts put Ozzy and Smudge under surveillance to find out who is king of the street and reveal why, no matter how hard we try, we can't keep our cats' hunting instincts under control.
The penultimate instalment investigates the primates, whose defining characteristics are forward-facing eyes for judging distance, and gripping hands with which to grasp branches, manipulate food and groom one another. The programme begins in Madagascar, home to the lemurs, of which there are some 20 different types. Two examples are the sifaka, which is a specialised jumper, and the indri, which has a well-developed voice. Away from Madagascar, the only lemur relatives to have survived are nocturnal, such as the bushbaby, the potto and the loris. The others were supplanted by the monkeys and a primitive species that still exists is the smallest, the marmoset. However, Attenborough selects the squirrel monkey as being typical of the group. Howler monkeys demonstrate why they are so named their chorus is said to the loudest of any mammal and their prehensile tails illustrate their agility.
We reveal the weird and wonderful stories of some of the natural world's incredible single parents: their devotion, dedication and often jaw-dropping endeavour in order to see their babies through to adulthood. From the slow loris covering her baby in toxic saliva to the Weddell seal putting her pup through winter boot camp, a weedy sea dragon cleverly camouflaging his eggs against his body and the female giant Pacific octopus sacrificing herself for her brood - we see how these parents are prepared to go the extra mile to arm the next generation with what they need to survive.