The film explores George Mallory's obsession with becoming the first person to reach the highest place on Earth. Told through the explorer's poignant and evocative letters to his wife, Ruth, previously unseen photos and film archive from 1924 (restored from the original nitrate especially for the film), dramatization and a modern-day expedition retracing the original route taken in 1924, Mallory's incredible adventure lives again. The expedition was led by renowned mountaineer Conrad Anker, whose life became inextricably linked with Mallory after he found Mallory s body on Everest in 1999. Using replica 1920s-era clothing and equipment, Anker sets out to solve the great mystery of whether Mallory succeeded in summiting Everest before he died he was last seen just 800 feet from the summit before the clouds closed in and he disappeared into legend. The most heart-breaking clue: All of Mallory's belongings were found intact on his body, except the photograph of his beloved Ruth, which he promised to leave at the top of the world if he succeeded.

Every year, over a thousand climbers try to reach the summit of Mount Everest, with the annual record for successful attempts currently standing at 633. But of that number, nearly half were Sherpas - the mountain's unsung heroes. Yet the Sherpa community has remained secretive about their nation, culture and experiences living in the shadow of the world's highest mountain. Now, for the first time, they open the door into their world. Without the expertise of the Sherpas, only the hardiest and most skilful climbers would succeed. Every day they risk their lives for the safety of others, yet they seek neither glory nor reward, preferring to stay in the background. Following the stories of four such Sherpas - Phurba, Ngima, Ngima Tenji and Gelu - this film reveals the reality of their daily lives, not just up the mountain, but with their families after they return home.

Between the 1920s and the 1960s the world's great powers sent vast military-style expeditions to conquer the peaks of the Himalayas, with Everest at their head. This was a great game played - camera in hand - by Imperial Britain, Nazi Germany and superpower America. As a result, Himalayan mountaineering's most iconic, epic and tragic moments didn't just go down in history, but were caught on film - from the deaths of Mallory and Irvine on Everest in 1924, to Everest's final conquest in 1953 by Hillary and Tensing. Using footage never before seen on British television, this is the story how of how film-makers turned the great peaks into great propaganda.

We are the only species on earth that cooks its food - and we are also the cleverest species on the planet. The question is: do we cook because we're clever and imaginative, or are we clever and imaginative because our ancestors discovered cooking? Horizon examines the evidence that our ancestors' changing diet and their mastery of fire prompted anatomical and neurological changes that resulted in taking us out of the trees and into the kitchen.

Do other worlds tremble and heave with geological life? On Mars, we found a volcano to dwarf Mount Everest. On the moons of the giants our understanding of volcanoes was changed forever.

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.