Destination Orion: Experts question ancient civilisations' fixation with the Orion constellation. Could this star group have been an entry point for aliens visiting Earth? (S4, ep 15)
Mystery Of Puma Punku: No one knows who designed and built Bolivia's sophisticated temple complex. Could it have been aliens? Experts investigate. (S4, ep 14)
Aliens And Dinosaurs: Theorists investigate a depiction of a stegosaurus found at Angkor Wat in Cambodia. Could it suggest that alien species killed off the dinosaurs? (S4, ep 13)
Time Travellers: Scientists explore the possibility that sightings of alien beings or UFOs may be evidence of time travellers from the future. (S4, ep 12)
The Da Vinci Conspiracy: Experts scrutinise the paintings, journals and technical drawings of Leonardo Da Vinci. Could they hide evidence of extra-terrestrial beings? (S4, ep 11)
Alien Power Plants: Ancient alien theorists ask whether the Greeks and Egyptians understood electricity. Could extraterrestrials have introduced them to such technology? (S4, ep 10)
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)
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 Bigfoot: Ancient astronaut theorists hunt for evidence linking Bigfoot to alien species from the distant past. Could the ape-like giant be an extraterrestrial? (S4, ep 7)
A desperate family asks Billy to help them with an aggressive bee colony that has taken over their entire house. Billy takes multiple stings and has to run from them. (S4 ep 10)