Saturn's secrets are out. The ferocious weather, the evolving ring system and the discovery of active geology on Saturn's moons has rewritten the textbooks. Scientists are looking for life on Saturn's moons and they may have found it on Titan.

A documentary-horror film exploring the phenomenon of 'Sleep Paralysis' through the eyes of eight very different people. These people often find themselves trapped between the sleeping and waking worlds, totally unable to move but aware of their surroundings while being subject to frequently disturbing sights and sounds. A strange element to these visions is that despite the fact that they know nothing of one another, many see similar ghostly 'shadow men.' This is one of many reasons many people insist this is more than just a sleep disorder". This documentary digs deep into not only the particulars of these eight people's uncanny experiences, but it also explores their search to understand what they've gone through and how it's changed their lives. Directed by Rodney Ascher, he chose to focus on sleep paralysis as it had happened to him in the past. The film's crew initially began approaching participants via message groups, videos and a half dozen books that had been written.

There's something very odd going on in space - something that shouldn't be possible. It is as though vast swathes of the universe are being hoovered up by a vast and unseen celestial vacuum cleaner. Sasha Kaslinsky, the scientist who discovered the phenomenon, is understandably nervous: 'It left us quite unsettled and jittery' he says, 'because this is not something we planned to find'. The accidental discovery of what is ominously being called 'dark flow' not only has implications for the destinies of large numbers of galaxies - it also means that large numbers of scientists might have to find a new way of understanding the universe. Dark flow is the latest in a long line of phenomena that have threatened to rewrite the textbooks. Does it herald a new era of understanding, or does it simply mean that everything we know about the universe is wrong?

The idea of intelligence is explored in the concepts of computers (using bits as their basic units of information), whales (in their songs and their disruptions by human activities), DNA, the human brain (the evolution of the brain stem, frontal lobes, neurons, cerebral hemispheres, and corpus callosum under the Triune Brain Model), and man-made structures for collective intelligence (cities, libraries, books, computers, and satellites). The episode ends with speculation on alien intelligence and the information conveyed on the Voyager Golden Record.

On a spectacular journey through Renaissance Italy, Andrew Graham-Dixon searches for the shadowy figure who wrote one of the most important books on art and looks at some dazzling works, including masterpieces of the early Renaissance by Giotto, Masaccio and Donatello. Giorgio Vasari was the grandaddy of all art critics, travelling Italy in the 16th century for his definitive Lives of the Artists. It was a time of miracles that he named 'the Renaissance'.

The episode, devoted to the planet Mars, begins with scientific and fictional speculation about the Red Planet during the late nineteenth and early twentieth centuries (H. G. Wells' The War of the Worlds, Edgar Rice Burroughs' science fiction books, and Percival Lowell's false vision of canals on Mars). It then moves to Robert Goddard's early experiments in rocket-building, inspired by reading science fiction, and the work by Mars probes, including the Viking, searching for life on Mars. The episode ends with the possibility of the terraforming and colonization of Mars and a Cosmos Update on the relevance of Mars' environment to Earth's and the possibility of a manned mission to Mars.