What happens when a series of strange and spectacular lights appear over Arizona? Giorgio A. Tsoukalos takes us through his top alien cover-ups including the supposed site of the UK's very own Area 51. Ancient Aliens examines 75 million years of the most credible alien evidence here on Earth: from the age of the dinosaurs, to ancient Egypt, to the skies over the western desert in the present day US, ancient cave drawings of strange creatures, an asphalt-like substance in an Egyptian pyramid made from the remains of unidentified creatures, continued mass sightings in the USA.