The big blue is the world's greatest wilderness, far from shore and many kilometres deep. It's a vast marine desert where there is little to eat and nowhere to hide. Yet it's home to some of the biggest and most spectacular creatures on earth. This episode reveals what it takes to survive in this savage and forbidding world. We witness feats of incredible endurance, moments of high drama and extraordinary acts of heart-wrenching self-sacrifice. Every animal in the big blue must find their own unique way to survive. Sperm whales have the largest brains in the world. They live for 80 years, and we are only now beginning to learn the extraordinary complexity of their language of clicks - thought to coordinate the whole family in everything from childcare to hunting. With special pressure-proof cameras, we witness record-breaking feats of endurance as they hunt for squid a kilometre down into the abyss. Only recently have we begun to solve the mystery of where baby turtles disappear to in their early years. They leave the crowded waters of the coast and head to the open ocean, where they use floating debris like logs as life rafts. Here they remain until adulthood, adrift on the high seas in relative safety away from coastal predators. Over half of all animals in the open ocean drift in currents. Jellyfish cross entire oceans feeding on whatever happens to tangle with their tentacles. The jelly-like Portuguese man-of-war can harness sail power to fish with its deadly tentacles. Sometimes there is a brief explosion of food in this marine desert, but ocean hunters must be fast to make the best of this bonanza. We witness super pods of up to 5,000 spinner dolphins racing to herd vast shoals of lanternfish, briefly caught at the surface where it is thought they spawn. New aerial footage reveals, for the first time, the truth to a centuries-old sailors' legend of the 'boiling seas' - the spectacular feeding frenzy of 90kg tuna and dolphins smashing through the lantern fish shoals turning the sea white with foam.

Bitcoin is the most disruptive invention since the Internet, and now an ideological battle is underway between fringe utopists and mainstream capitalism. "Banking on Bitcoin" shows the players who are defining how this technology will shape our lives. Bitcoin's early pioneers sought to blur the lines of sovereignty and the financial status quo. After years of underground development Bitcoin grabbed the attention of a curious public, and the ire of the regulators the technology had subverted. After landmark arrests of prominent cyber criminals Bitcoin faces its most severe adversary yet, the very banks it was built to destroy.

Our planet is one in a billion. How incredible, awe-inspiring life is driven by its natural forces - and how we can ensure humans become a force for good. David Attenborough narrates a series revealing how the forces of nature drive, shape and support the Earth's great diversity of life.
The first edition examines volcanoes, which responsible for both for the planet's breathable atmosphere and the oceans, but are also the architects of the planet, with over 80% of the Earth's surface being the result of magma bursting up from the molten interior - providing a platform for life.

Dr Janina Ramirez unlocks the secrets of illuminated manuscripts that were custom-made for kings and explores the medieval world they reveal. 'Ruling by the Book.' Janina begins her journey with the first Anglo-Saxon rulers to create a united England, encountering books in the British Library's Royal manuscripts collection which are over a thousand years old and a royal family tree which is five metres long.
Janina finds out about a king who had a reputation for chasing nuns and reads a book created as a wedding gift for a ten-year-old prince. She roams from Westminster Abbey to other ancient English spiritual sites such as Winchester, St Albans and Malmesbury, and sees for herself how animal skins can be transformed into the finest vellum.

America says eight out of ten industrial espionage cases now involve China. Governments around the world are uncovering secret operations to expand China's influence - the work of a little-known branch of the Chinese Communist Party called the United Front Work Department. President Xi has called it his 'magic weapon'.
Jane Corbin investigates this powerful but shadowy organisation. Has influence become interference as China bids to become the most powerful nation on earth?

The Cave of Swallows in Mexico is a 400m vertical shaft, deep enough to engulf the Empire State Building. The Lechuguilla cave system in the USA is 193km long and 500m deep with astonishing crystal formations hanging from its chambers. Although often overlooked, caves are remarkable habitats with equally bizarre wildlife. Cave angel fish cling to the walls behind cave waterfalls with microscopic hooks on their flattened fins. Cave swiftlets navigate by echo-location and build nests out of saliva. The Texas cave salamander has neither eyes nor pigment. Unique access to a hidden world of stalactites, stalagmites, snotites and troglodytes brings a wealth of surprises.