In 2010 the UK Ministry of Defence declassified decades of UFO files, and this film goes through what they actually contain: sighting reports, military correspondence, and investigations spanning the length of Britain. Among the cases are a wartime incident Winston Churchill is said to have ordered suppressed, an alleged UFO crash in Wales, and a Boeing 737 pilot's account of an object crossing his flight path over Manchester. Alongside the case files, the film looks at why Britain kept taking these reports seriously for so long, tracing the shift from wartime fears of enemy aircraft to the postwar spread of science fiction and how both fed public expectations of what an unidentified object might be. Historians and researchers work through the documents on camera, weighing which reports look like misidentified aircraft or weather phenomena and which resist easy explanation. The film stops short of claiming proof of extraterrestrial visitors, treating the files instead as a record of what a government was willing to write down and investigate, and asking why it bothered.