David Attenborough concludes his epic history of the evolution of flight with an exploration of the highly advanced fliers that dominate our skies today – the extraordinarily diverse skills of the birds, and the sonar-guided precision of the bats. He encounters some of our planet’s most remarkable fliers – from peregrine falcons dive-bombing starlings over Rome, to hummingbirds hovering in the cloud forests of Ecuador. In a spectacular finale, he visits Gomantong cave in Borneo to witness the mass exodus of a million bats.

David Attenborough continues his search for the origins of flying animals, as he charts the rise of new, larger creatures – extinct reptiles that flew on wings of skin, dinosaurs that sprouted feathers to become the ancestors of birds, and gliding mammals that emerged from a life in the trees to dominate the night as bats. His journey spans the globe – from the rainforests of Borneo to see bizarre gliding animals, to China and its new discoveries of dinosaur fossils. Stunning CGI brings to life creatures that disappeared over 200 million years ago, and new filming techniques bring us closer than ever to the secrets of flight itself.

Deep in the Andean mountains lays a mysterious ruin named Machu Picchu. For 400 years it sat abandoned on its misty cliff, the quintessential lost city in the jungle. Rediscovered in 1911, it contained no written records or carvings, nothing that could shed light on its history. For a century since, it has defied the endless scores of visitors and scientists who attempted to understand its purpose. Who were the mysterious people who built it and why did they build it here? Today an international team of archaeologists, engineers and scientists are finally piecing together the clues. Together they are discovering astonishing new burials, revealing the intricacies of its ingenious engineering and finally decoding the secrets of Machu Picchu.

A new age of space exploration is dawning. But surprisingly, some of the boldest efforts at putting humans into space are now those of private companies started by a handful of maverick billionaire businessmen. In this film, Brian Cox gains exclusive access behind the scenes at Virgin Galactic, Blue Origin and Spaceport America, exploring what is really happening in privately financed space flight right now.

Dr. Thomas Asbridge introduces the epic story of the Crusades – a tale of religious fanaticism and unspeakable brutality, of medieval knights and Jihadi warriors; of castles and kings; of heroism, betrayal, and sacrifice. He explains how, using fresh evidence, eye-witness testimonies and contemporary accounts – from both the Christian and Islamic worlds – we are able to re-examine this epic medieval drama, and how he has retraced the steps of the Crusaders from a small town in France to the magnificent cities of the Holy Land, bringing to life the human experience of the Crusades, and shedding new light on how it was that two of the world’s great religions waged war in the name of God.

Could we get all our energy needs from sea water and the salt it contains? Are we to witness a time when salt will power our engines and factories, and light up our cities? Could this be the final curtain not only for shale gas and oil, but also the burning of fossil fuels and the beginning of a gentler form of energy that is definitely renewable? This documentary explores the latest research on sea water and the way scientists all over the world are working on 'Blue Energy'. This research could bring about a major change in our time.