The Blue Marble is an image of Earth taken on 1972, from a distance of about 18,000 miles from the planet's surface. It was taken by the crew of the Apollo 17 spacecraft on its way to the Moon. Before it was photographed from space, our perspective of Earth was fragmented and disconnected. Recent discoveries have revealed a dynamic and rapidly changing planet, above the crust and below.

Genetic breakthroughs have shed light on how life evolves in real-time. From filling in the missing links to creating a new species, in the last 50 years scientists have solved some of the biggest mysteries of evolution. In this episode, we look at revolutionary discoveries that shook the world and may shape our future.

COVID-19 is far from the first pandemic to wreak havoc in the world. A long line of infectious diseases have devastated and in some cases destroyed entire societies. Almost all of them started in animals and made the jump to humans. The Black Death spread across Europe and Asia in the 14th century leaving millions dead in its wake. Between the 15th and 18th centuries, European colonists brought smallpox to the Americas, the Pacific region and to Australia. In Europe, the 17th century saw a series of major epidemics. And at the end of the First World War, more people died of the Spanish flu than on the battlefield.
This documentary examines the causes of these epidemics - whether it be lack of hygiene, interaction with animals, overcrowding, or the growth of cities - and how people travelling helped to spread disease and promote pandemics. It also sheds a light on the impact these infectious diseases have had on politics and societal change. Over the centuries, scientists managed to develop treatments and medicines to help control or even eradicate infectious diseases. Virologists are facing that task again with the coronavirus, as the world frantically searches for ways to overcome a pandemic which threatens our modern way of life.

As the journey continues, there's beauty and danger in equal measure. Charley and Ewan travel through the extraordinary Bolivian desert, but the sandy roads make all more difficult. The duo ride their electric bikes through the exotic and breathtaking countryside and all the way making a challenging ascent. The riders stay in a hotel made entirely out of salt before heading to La Paz. 'Bolivia' also shows some quality work done by UNICEF when it comes to educating and working with the children. McGregor and Boorman spend time with the kids before resuming their journey and ending with a ferry ride over lake Titicaca.

Ewan and Charley make their way to Peru from Bolivia, and the scenery is just beautiful. Ewan wanted to visit Machu Picchu since he was a kid and decides to show the world the Incan citadel set high in the Andes Mountains. Next up, they make their way to the Cutivireni, a community of Ashaninka people in the Amazon rainforest, with its carbon program to limit the magnitude or rate of global warming and its related effects.

For Charley Boorman and Ewan McGregor, their journey in the smooth Ecuadorian roads would most definitely have come as a relief after some rough terrain riding. Next up, they stop by one of the factories that make the famed Panama hats. One of the local producers explains that making them by hand takes roughly up to a month. At the other end, the crew on the Rivians make a dash for Central America where they have to ferry their trucks across as the Darién Gap blocks their path. On their way, they make a quick pitstop at one of the cacao factories to know more about cocoa production, one of the economic drivers of the country.