Iain explores man's relationship with fire. He begins by embarking on an extraordinary encounter with this terrifying force of nature - a walk right through the heart of a raging fire. Fire has long been our main source of energy and Iain shows how this meant that the planet played a crucial role in Britain's industrial revolution, whilst holding China's development back. Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt, crawls through an extraordinary cave in Iran and takes a therapeutic bath in crude oil.

In the last of the series, Julian Richards uncovers new information from the battle in 1066 between Viking warlord Harald Hardrada and King Harold of England that marked the end of the Viking age in Britain. Results from a nationwide genetic survey show where in Britain the Vikings left a measurable contribution.

From stars, galaxies and moons to subatomic particles, black holes and invisible phenomena, discover the most bizarre, mysterious and exotic things in our universe

Professor Brian Cox travels from the fossils of the Burgess Shale to the sands of the oldest desert in the world to show how light holds the key to our understanding of the whole universe, including our own deepest origins. To understand how light holds the key to the story of the universe; you first have to understand its peculiar properties. Brian considers how the properties of light that lend colour to desert sands and the spectrum of a rainbow can lead to profound insights into the history and evolution of our universe. Finally, with some of the world's most fascinating fossils in hand, Brian considers how but for an apparently obscure moment in the early evolutionary history of life, all the secrets of light may have remained hidden. Because although the universe is bathed in light that carries extraordinary amounts of information about where we come from, it would have remained invisible without a crucial evolutionary development that allowed us to see. Only because of that development can we now observe, capture and contemplate the incredible wonders of the universe that we inhabit.

This episode focuses on the Jurassic period, a time when the first giant killers stalked the Earth and lurked in the seas; a time when the slightest advantage meant the difference between life and death. In North America the iconic allosaurus, an ambush hunter with a lethal bite, dominated. Not even the heavily-armoured stegosaurus was safe from this killer, and incredible evidence reveals a glimpse of a vicious battle between these two giants. Life in Jurassic oceans was no easier; in 2008, a fossil was dug out of a frozen island high in the Arctic. It was a colossal marine reptile, twice as big as most ocean predators, at 15 metres long and weighing about 45 tonnes. This was Predator X. Its skull alone was nearly twice the size of a tyrannosaurus rex's, and its bite force unmatched by anything in the Jurassic seas. The balance of power between predator and prey is a fine one, as prey continually evolves different ways to avoid predators. But for the most successful and enduring predators, the battle to survive has always been tipped in their favour

In episode two, we discover the golden age of the La Tene Celtic warrior and reveal how their world extended as far as central Turkey. But by the middle of the first century BC, the Celts were under threat from an expanding Roman Empire, and the Gallic warrior Vercingetorix would challenge Julius Caesar in an epic battle that would shape the future of Europe.