This is the story of two tiny animals coming of age. In the wild woods of North America, a young chipmunk is gathering a vital store of nuts ahead of his first winter - in his way are ruthless rivals and giant predators. In the steaming rainforest, a young tree-shrew is forced deep into the jungle to find food. She must draw on all her intelligence and agility if she is to escape the ultimate jungle predator - a reticulated python!

Is mankind alone, or are there aliens out there, either waiting to be discovered, or on their way to find Earth? Professor Brian Cox spends this episode asking such questions, and what he discovers may raise a few eyebrows. He begins by exploring the human race's efforts to find neighbours in outer space, including the launch of two golden discs containing a greeting from Earth in the 1970s; they are still travelling and are now the most distant man-made objects from the planet. Brian also meets members of the Search for Extra-Terrestrial Intelligence, who have been monitoring radio signals for 50 years without success, before discussing the ingredients needed to make an intelligent civilisation with astrophysicist Dr Frank Drake.

Citizenfour received the Academy Award for Best Documentary Feature at the 2015 Oscars. The film was directed by Laura Poitras concerning Edward Snowden and the NSA spying scandal." In January 2013, Laura Poitras received an encrypted e-mail from a stranger who called himself Citizen Four. In it, he offered her inside information about illegal wiretapping practices of the NSA and other intelligence agencies. Poitras had already been working for several years on a film about monitoring programs in the US, the result of the September 11 attacks. In June 2013, accompanied by investigative journalist Glenn Greenwald and The Guardian intelligence reporter Ewen MacAskill, she went to Hong Kong with her camera for the first meeting with the stranger, who identified himself as Edward Snowden. Several other meetings followed. The recordings gained from the meetings form the basis of the film.

Is God worshipped in other worlds, across the cosmos? How might alien deities differ from our own? The answer may lie buried on Earth. Animal behaviorists are testing elephants and finding them capable of having spiritual thoughts. Artificial intelligence researchers are building enlightened robots that contemplate the divine. Meanwhile, cosmologists are looking for universal equations that could replace God. Have advanced aliens discovered everything there is to know about the universe? Or are they looking to a higher power for answers?

There could be an undiscovered species on Earth unlike anything we’ve ever known. Not in the ocean, but the ocean itself! Its body spans thousands of miles; its heart beats with a one-thousand-year pulse. It could even have an immune system capable of annihilating all other life on earth. Just as our bodies function through the interaction of water with individual cells, including bacteria and other microorganisms, the ocean’s residents might collectively form a super-organism. A recent discovery suggests the ocean is a living being capable of thought. If so, what is the ocean thinking about us?

Humanity’s potential seems limitless. But could we become as powerful as God? Scientific breakthroughs grant our species seemingly divine abilities. Biologists tinkering with DNA are figuring out ways to grow new life forms, while neuroscientists try to create artificial consciousness. Statisticians around the world are using big data to predict the future and computer scientists have discovered a "God algorithm" that could solve any global problem in an instant. But to truly become God, we not only have to be all knowing, but all being. Quantum physicists are figuring out how to teleport matter at the speed of light!