In 1914, Russia entered World War I in response to Austria-Hungary's declaration of war on Russia's ally Serbia. This was fought across multiple fronts while isolated from its allies. The Battle of Tannenberg, where the entire Russian Second Army was annihilated, cast an ominous shadow over the empire's future. The already-existing public distrust of the regime was deepened by the rising costs of the war and rumours of corruption. World War I takes Nicholas to the front. Back home, outrage grows over high casualties and Alexandra and Rasputin's political intrigues.

Stars helped create us, building and spreading the ingredients for life to develop. But there will definitely be a point in the future when, in the future when, you look up, you will no longer be able to see stars.
For billions of years, stars brought life to the universe. Now, they're dying out in a star apocalypse. What's causing the die-off, and what happens to life when the lights go out?

As tides rise and fall twice a day, vast amounts of water swirl around the earth. This is a huge energy source that's currently largely untapped. An estimated 3000 gigawatts are available to be harvested globally, enough to power a third of the earth's homes. Yet compared to wind and solar, the technology needed to harness tidal power is still in its infancy. The power of the ocean’s tides is the last great untapped energy source on Earth. From sub-sea kites to floating platforms, teams of engineers are racing to perfect the technology to harness the vast flows of water.

The world's shipping industry is facing a major challenge. If global shipping were a country it would be the sixth largest producer of greenhouse gas emissions. At current growth rates, if we do nothing, those emissions could double or even triple by 2050. But shipping companies and engineers are creating remarkable new machines to make their industry greener, using a resource that has moved man across the world’s oceans for thousands of years…Wind.

A new force threatens our perfect planet. In the past, five mass extinction events were caused by cataclysmic volcanic eruptions. It was not the lava or ash that wiped out life, but an invisible gas released by volcanoes: carbon dioxide. Almost every part of modern life depends on energy created by burning fossil fuels, and this produces CO2 in huge amounts. Humans are changing our planet so rapidly, it’s affecting earth’s life support systems: our weather, our oceans and the living world. The greatest change to be made is in how we create energy, and the planet is brimming with natural power that can help us do just that. It’s these forces of nature - the wind, the sun, waves and geothermal energy - that hold the key to our future.
Through compelling animal-led stories and expert interviews, we discover how CO2 is destabilising our planet. We meet rescued orphaned elephants in Kenya, victims of ever worsening droughts, and join ocean patrols off the coast of Gabon fighting to save endangered sharks. In the Amazon, we witness wildlife teams saving animals in the shrinking forests, and in San Diego we enter a cryogenic zoo preserving the DNA of endangered species before they become extinct.

There is a region of space that is dangerous for reasons we don't yet understand completely. We see an increased flux of energetic particles in this area and higher-than-usual levels of radiation. It's called the South Atlantic Anomaly. Some scientists now think the long-term effects of this danger zone may be far wider reaching than anyone ever expected, and it may even have implications for the future of humanity in space and on Earth.