Explore the paranormal with host Robert Stack in this collection of the best of Unsolved Mysteries - UFOs. Dozens of crop circles, up to 100 feet across, are being carved in the countryside. Are they a freak of nature or UFO landing pads? Did life on Earth begin on Mars? A startling new theory emerges. Roswell and Area 51...UFO crash site or government cover-up? Judge for yourself as host Robert Stack takes you behind the scenes of these and other best of the unexplained encounters.