The skies above have always fascinated and mystified us. But there are few explanations as compelling and as universally sought as this: 'Why are there so many reports of UFOs throughout the world?' Is it conceivable that we have borne witness to craft and beings from other planets in our skies? Many times the stuff of science fiction movies, the fact remains that there have been a huge amount of real life reports of unidentifiable aircraft and mysterious airborne objects. Many have been dismissed as the products of unreliable witnesses or hoaxes. But a few are harder to explain away. Invasion Earth investigates the world’s most intriguing and fascinating UFO sightings. It retells and reconstructs incidents from all over the world, many recent, some dating back decades. It seeks out first-hand eye-witnesses and listens to their compelling accounts - some too frightened to go public until now. Previously classified official documents are uncovered. And with the help of a distinguished panel of aviation, military and scientific experts, all the evidence is thoroughly examined and tested. Could there be more down-to-earth man-made explanations for any of these sightings? Why so much secrecy from investigating officials? Or must the truth be hidden from us ensuring these shall always remain the secrets of the skies?