Across the universe, galaxies are going dark, and scientists don't know why the stars are losing their shine. Something is slowly drawing the curtains closed on the universe. Our milky way is under threat. Astronomers race against time to uncover the truth behind how galaxies are born and how they die before all of the lights go out.

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.

Most planets we know of are so hellish, it seems impossible that anything could live. But it's amazing where life can take hold in the Earth. Astrobiologists look for simple single-celled microbes known as extremophiles in places as Danakil Depression, known in Ethiopia as 'The Gateway to Hell.'
In Episode 2, the fictional world is Janus, a planet in such a close orbit than its rotation is locked by the star's gravity and it always shows the same face to its sun. On one side of the planet, it's always daytime, a searing desert. On the other side, it's forever night, a frozen shadowland. Squeezed between the two, a sliver of perpetual twilight. Freezing meltwater flows from the cold side, carving canyons through the landscape. Deep in these canyons lives an extraordinary five-legged creature.

Planets beyond our solar system are known to astronomers as exoplanets. They are at trillions of miles from Earth and yet, it might be possible to detect a faint signature of life in them. From the light of the stars they orbit that passes through the atmosphere of an exoplanet, it is possible to capture the chemical fingerprint of the elements in that atmosphere.
The fictional world Eden is orbiting not one star, but two. The light from its twin stars powers photosynthesis, pumping more oxygen into the atmosphere than in Earth, allowing life to thrive. Grazers are constantly alert to danger, because the canopy is home to predators perfectly evolved to live among the trees. In Episode 3, another topic are fungi and the role they could play on exoplanets. Ecologist Thomas Crowther talks about the role mycelial networks play in the Rothiemurchus forest in Scotland.

What sort of alien civilizations might exist in the vastness of space? Terra is the fictional world imagined in Episode 4, a planet nine billion years old, twice as old as Earth. Old enough that a truly advanced intelligence could evolve. It was once a fertile world, now it is barren. But life can still thrive here in artificial domes. Over time, they've evolved not to need their bodies. They exist only as neural tissue. They never age, they never die. They're monitored and maintained by robots.
If alien civilizations are statistically so likely, why haven't astronomers found any sign of them? Where is everyone? Every time we look at an individual star, that's like dropping a bucket in the ocean. We're going to have to look at a lot of stars and to search through a lot of data until we find the clue that leads us to another civilization.

In August of 2018, Greta Thunberg, a 15-year-old student in Sweden, starts a school strike for the climate. Her question for adults: if you don't care about her future on earth, why should she care about her future in school? Within months, her strike evolves into a global movement. Greta, a quiet Northern-European girl on the autism spectrum is now a world famous activist. The team behind Greta has been following the young activist from her very first day of school striking. The documentary shows the international crusade of Greta on in her goal to get people to listen to scientists about the world's environmental problems.