Alien Operations: Experts investigate reports of bird-like figures that practised advanced medical science in ancient times. Could they have been extra-terrestrial? (S5, ep 9)

Aliens And Cover-ups: In 1980, a man received a code after touching an alleged spaceship. After the sequence was translated, he was told never to speak of the incident again. (S4, ep 9)

Aliens And Deadly Weapons: From gunpowder to missiles, were these lethal weapons the product of human innovation, or were they created with help from another, otherworldly source?

Unexplained Structures: Could aliens have helped humans build huge ancient structures? Experts ask whether standing stones in France, were a GPS system for ancient spacecraft. (S2, ep 9)

Circles from the Sky: Crop circles are a global phenomenon, with 10,000 seen worldwide. But are these strange patterns simply a hoax or could they be proof of UFO activity? (S8, ep 8)

The Great Flood: Experts find evidence suggesting that ancient aliens saved humanity from great floods sent by the gods. Can we rely on extra-terrestrials to save us again? (S7, ep 8)

Aliens And The Red Planet: Experts question what probes on Mars may have found over the past 40 years. Could NASA be hiding proof of life on the Red Planet from the public? (S6, ep 8)

Emperors Kings And Pharoahs: Could ancient rulers have had otherworldly links? Experts examine whether history's most powerful leaders were 'chosen' and guided by aliens. (S5, ep 8)

Einstein Factor: Ancient astronaut experts believe the minds of Einstein and Galileo were superhuman. Could these historical geniuses have had extraterrestrial connections? (S4, ep 8)

Aliens And Lost Worlds: Experts search for proof of alien visitors in the ruins of lost civilisations. Could Mayan carvings reveal a city once ruled by otherworldly beings? (S3, ep 8)