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.

Rome was once a largely democratic society, with regular elections. This Republic lasted for 500 years, but then came Tiberius Gracchus. He believed in the ideals of the Republic - fairness, decency and justice for everyone -but was appalled by Rome's aristocrats' treatment of the poor. So he unleashed the power of the mob upon the streets of Rome, with devastating consequences.

Albert Einstein, the most famous scientist of all time, was a world-renowned celebrity, greeted like a rock star when he appeared in public. An anti-war firebrand, Einstein also spoke out on issues ranging from women's rights and racism to immigration and nuclear arms control. But today, his image has been neutered into that of a charmingly absent-minded genius. He was, in fact, a powerful force for social change and a model for political activism.
Using a wealth of rarely-seen archival footage, correspondence, and new and illuminating interviews, filmmaker Julia Newman makes the case that Albert Einstein's example of social and political activism is as important today as are his brilliant, groundbreaking theories.

Here, Aleks charts how the Web is forging a new brand of politics, both in democracies and authoritarian regimes. With contributions from Al Gore, Martha Lane Fox, Stephen Fry and Bill Gates, Aleks explores how interactive, unmediated sites like Twitter and YouTube have encouraged direct action and politicised young people in unprecedented numbers. Yet, at the same time, the Web's openness enables hardline states to spy and censor, and extremists to threaten with networks of hate and crippling cyber attacks.

Can new emission-free electric planes replace our polluting airliners and revolutionize personal transportation in our cities? The film takes a ride in some quiet, energy-efficient, prototypes that are vying for success as electric flight takes off.
The race is on to stop the climate emergency and we're seeing more and more people really paying attention to their carbon footprint. Aviation is a fast-growing offender, but is it too slow to respond. Could rapid progress in electric technology change the equation?

In the last episode, Al-Khalili turns detective, hunting for clues that show how the scientific revolution that took place in the 16th and 17th centuries in Europe had its roots in the earlier world of medieval Islam. He travels across Iran, Syria and Egypt to discover the huge astronomical advances made by Islamic scholars through their obsession with accurate measurement and coherent and rigorous mathematics.He then visits Italy to see how those Islamic ideas permeated into the west and ultimately helped shape the works of the great European astronomer Copernicus, and investigates why science in the Islamic world appeared to go into decline after the 16th and 17th centuries, only for it to re-emerge in the present day. Al-Khalili ends his journey in the Royan Institute in the Iranian capital Tehran, looking at how science is now regarded in the Islamic world