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.

Professor Brian Cox grapples with science's darker side, asking why, when science has done so much for us, it often gets such a bad press. Starting with the original Frankenstein - the grisly 19th century tale of George Foster's hanging and subsequent 'electrocution', Brian confronts the idea that science can go 'too far'. From the nuclear bomb to genetic modification, British science has always been at the cutting edge of discovery, but are British scientists feckless meddlers, or misunderstood visionaries whose gifts to humanity are corrupted by the unscrupulous?

For one night only, Professor Brian Cox goes unplugged in a specially recorded programme from the lecture theatre of the Royal Institution of Great Britain. In his own inimitable style, Brian takes an audience of famous faces, scientists and members of the public on a journey through some of the most challenging concepts in physics. With the help of Jonathan Ross, Simon Pegg, Sarah Millican and James May, Brian shows how diamonds - the hardest material in nature - are made up of nothingness; how things can be in an infinite number of places at once; why everything we see or touch in the universe exists; and how a diamond in the heart of London is in communication with the largest diamond in the cosmos.