Over the last thirty years there have been thousands of reported sightings of unidentified flying objects over the British Isles. Numerous eye-witnesses have testified to seeing strange lights in the sky and other mysterious phenomena. Many of these UFO sightings remain unexplained to this day, but what, or who, where they? Could they really be evidence of extraterrestrial life? Britain's Closest Encounters looks at four of the most astonishing and baffling UFO stories in Britain and hears first-hand from those who witnessed some of these sightings and examines the truth behind some of Britain's most celebrated UFO sightings.