What if we could travel not just through space, but through time itself? If you could travel through time, would you change the past or the future? What if you found it couldn’t be changed? What price does the time traveller -- and the people they are closest to -- pay? This is a journey from H. G. Wells' The Time Machine through ideas like The Grandfather Paradox and The Butterfly Effect to the professional time traveller that is the ever popular Doctor Who. Steven Moffat, David Tennant, Karen Gillan, and Neil Gaiman offer a unique perspective on the Doctor. Edward James Olmos reveals the hidden meaning of the language he created for the vision of the future that is Blade Runner. Bob Gale and Christopher Lloyd take us behind the scenes of Back to the Future, while Ed Solomon describes the joy of solving a time travel conundrum for Bill & Ted’s Excellent Adventure. But what would be the physical and emotional cost to the time traveller? Audrey Niffenegger explains what inspired her novel The Time Traveller’s Wife. And what if someone from the future tried to travel back in time to warn us? Would we believe them? From the apocalyptic tones of 12 Monkeys to the drama of Quantum Leap and the comedy of Groundhog Day, time travel is a subject that has been irresistible to the creators of every type of science fiction.

What if aliens landed on Earth? Much of science fiction explores the moment of first contact – what will people do when the aliens land? From H. G. Wells’ pioneering The War of the Worlds to Independence Day, Men in Black, and District 9, Invasion deals with our fears of alien invasions of earth. David Tennant explains the appeal of Doctor Who’s Daleks and Cybermen while John Carpenter and Chris Carter explore the rich appeal of the paranoia fuelled by hidden aliens with The Thing and The X-Files. It also asks, what if the monsters were our own creation? With the aid of rarely seen animation tests, Phil Tippett takes us behind the scenes in the creation of the dinosaurs of Jurassic Park. But not all invasions are hostile. Peter Coyote and Richard Dreyfuss discuss the creation of Spielberg’s spellbinding classics E.T. the Extra-Terrestrial and Close Encounters of the Third Kind. There is more than one kind of invasion.

What if we could explore the vastness of Space? Science fiction has always fed upon our need to explore – to wonder what is out there. Space journeys from Jules Verne’s earliest ideas about attempts to leave our planet, to the Star Wars far away galaxy through to Nichelle Nichols revealing how her groundbreaking role as Lt. Uhura in Star Trek led to her participation in the recruitment of NASA’s astronauts. It explores the deep sea inspiration for Avatar, finds out why Ursula K Le Guin wrote The Left Hand of Darkness and discovers how Stanley Kubrick was able to make 2001: A Space Odyssey seem so believable. In addition, the program looks at the way Dune and The Mars Trilogy embraced the challenge of world building and discusses the appeal of the beaten up ‘dirty space’ of Dark Star and Firefly. From the horrifying scenes of Alien, to the epic spectacle of Star Wars, this is a journey to the stars and the alien encounters that await us there.

The series heads to the very frontiers of space and science to produce the definitive history of science fiction. What if our creations turn against us? The idea of creating life has fascinated society since the earliest days of science fiction. Robots transports viewers from the first steps of Frankenstein’s monster to the threat provided by the Terminator and the world of Cyberspace. Find out how Rutger Hauer created one of the greatest speeches in all of science fiction for Blade Runner. Discover from Kenny Baker the challenge of acting in Star Wars while inside the body of R2D2, and learn how Anthony Daniels was drawn to the role of C-3PO by concept art modeled closely on the robot from the silent classic Metropolis. The creators of the original Robocop describe how its hidden depths have given it enduring appeal and William Gibson reveals the origins of his seminal novel Neuromancer. From HAL in 2001: A Space Odyssey to the Cylons of the reimagined Battlestar Galactica and the world of The Matrix, this is a journey that asks – what does it mean to be human?

Dr. Thomas Asbridge explains how in the thirteenth century, after almost two hundred years of Holy Wars, the titanic conflict between Christianity and Islam, known to history as The Crusades, reached a decisive and shocking conclusion – a chapter that despite its drama has been virtually forgotten. He explains how, in the end, the fate of the Holy Land was decided not on the hallowed ground of Jerusalem, but in Egypt; and how the ultimate outcome of the Crusades was dictated not by Christians, but by the Mongol successors to Genghis Khan, and by a Muslim slave – a fearsome warrior whose story is now all but lost to western history.

Researchers discover film footage from World War II that turns out to be a lost documentary shot by Alfred Hitchcock and Sidney Bernstein in 1945 about German concentration camps liberated by allied troops. When Allied forces liberated the Nazi concentration camps in 1944-45, their terrible discoveries were recorded by army and newsreel cameramen, revealing for the first time the full horror of what had happened. Making use of British, Soviet and American footage, the Ministry of Information’s Sidney Bernstein (later founder of Granada Television) aimed to create a documentary that would provide lasting, undeniable evidence of the Nazis’ unspeakable crimes. He commissioned a wealth of British talent, including editor Stewart McAllister, writer and future cabinet minister Richard Crossman – and, as treatment advisor, his friend Alfred Hitchcock. Yet, despite initial support from the British and US Governments, the film was shelved, and only now, 70 years on, has it been restored and completed by Imperial War Museums. This eloquent, lucid documentary by André Singer (executive producer of the award-winning The Act of Killing) tells the extraordinary story of the filming of the camps and the fate of Bernstein’s project, using original archive footage and eyewitness testimonies.