As the journey continues, there's beauty and danger in equal measure for Charley Boorman and Ewan McGrego. The duo ride their electric Harleys through the exotic and breathtaking Bolivian countryside in a tough ascent. The sixth episode showcases some of the challenges the hosts and the crew face when they scale the terrain. One of the Rivians runs into trouble while sandy roads and a heavy breeze sees Boorman take a tumble. Apart from all the accidents, the chapter also shows some quality work done by UNICEF when it comes to educating and working with the children in Bolivia.
The altitude sickness hits Taylor, their logistics man real bad and McGregor starts feeling it as well. The episode ends with a doctor heading to his hotel room to check up on him.

David Attenborough returns to the island of Madagascar on a very personal quest. In 1960, he visited the island to film one of his first ever wildlife series - Zoo Quest. Whilst he was there, he acquired a giant egg belonging to an extinct bird known as the 'elephant bird' - the largest bird that ever lived. It has been one of his most treasured possessions ever since. Fifty years older, he now returns to the island to find out more about this amazing creature and to see how the island has changed. Could the elephant bird's fate provide lessons that may help protect Madagascar's remaining wildlife?
Using Zoo Quest archive and specially shot location footage, this film follows David as he revisits scenes from his youth and meets people at the front line of wildlife protection. On his return, scientists at Oxford University are able to reveal for the first time how old David's egg actually is, and what that might tell us about the legendary elephant bird.

A remarkable 200-million-year-old fossil - the bones of an ichthyosaur, a giant sea dragon - has been discovered on the Jurassic coast of Britain. David Attenborough joins the hunt to bring this ancient creature's story to life. Using state-of-the-art imaging technology and CGI, the team reconstruct the skeleton and create the most detailed animation of an ichthyosaur ever made. Along the way, the team stumble into a 200-million-year-old murder mystery - and only painstaking forensic investigation can unravel the story of this extraordinary creature's fate.

Sir David Attenborough chooses his favorite recordings from the natural world --from the song of the largest lemur to the song of the humpback whale to the song of the lyrebird-- that have revolutionized our understanding of song. The science of song had been transformed by Charles Darwin’s theory of sexual selection: singing is dangerous as it reveals the singer’s location to predators, but it also offers the male a huge reward, the chance to attract a female and pass on genes to the next generation. Today, new science in the field of birdsong is transforming those long-held ideas.
Scientists are discovering that, in fact, in the majority of all songbird species, females sing - and it is only now they are being properly heard. Through this revelation and others, we can understand that animal songs are marvellous examples of the spectacular survival strategies that species have developed.

Audrey Hepburn was a film and fashion icon of the twentieth century and one of the most beloved actresses of all time. She enchanted the world with elegance and innocent charm, and portrayed some of the most memorable characters in film. Although she was one of the few actresses to win an Emmy, Tony, Grammy, and Academy Award, Audrey was modest about her talents, often claiming she had no acting technique. She redefined glamour with elfin features and a waif-like figure that inspired timeless designs by Hubert de Givenchy.Raised in the Netherlands during World War II, Audrey never forgot her own struggles during the German occupation and dedicated her later years to helping needy children around the world, becoming an International Goodwill Ambassador for UNICEF and traveling around the world to provide aid. Audrey Hepburn is remembered as a natural talent, a timeless beauty and a great humanitarian.

Foo Fighters prepare to record at the Austin City Limits Studio, with blues guitarist Gary Clark, Jr. In this episode is examined the roots of Austin's music scene, with interviews featuring Billy Gibbons from ZZ Top, and Roky Erickson from 13th Floor Elevators, who is considered one of the American fathers of psychedelic rock. Dave also chats with Terry Lickona, the executive producer of Austin City Limits. The song 'What Did I Do? / God As My Witness' is recorded during this chapter.