A housewife in Staffordshire saw two space-suited men looking down at her from a huge metallic disc. A peasant in Brazil reported being taken into a spacecraft, and was later said to be suffering from exposure to radiation. Hundreds of similar accounts have come in from all over the world and many theories have been advanced about what is going on. In tonight's documentary, Hugh Burnett talks to some of the people who have seen strange things and others who have been puzzling over what, to them, is a very alarming phenomenon.