Every year, thousands of people all over the world report seeing an unidentified flying object, or UFO. There are also numerous and eerily similar stories of people being abducted by alien creatures, reports of unexplained crop circles and cattle mutilations. This overwhelming body of evidence leads our investigators to ask, "If it isn't aliens, what is it?" In this episode of Legend Hunters, we follow the world's leading researchers in their quest to once and for all solve one of the greatest mysteries of the modern world and perhaps prove that we are indeed not alone.