Throughout history, there are stories of strange beings unlike anything known to exist on Earth. Could they be more than just mythology? Could our ancestors' descriptions of heavenly visitors with bird-like wings be evidence of contact with extraterrestrial visitors called angels? Did giants really walk the Earth thousands of years ago? And if so, could they have been from another world? Or perhaps even the result of alien experimentation with our own DNA? Is it possible that elongated skulls found on numerous continents are evidence of humans mimicking the appearance of otherworldly visitors, as Ancient Astronaut theorists suggest? Or could they even be the skulls of extraterrestrials themselves? Could ancient history hold clues to the possibility that we have been visited in the past by extraterrestrials? If so, did they come to shape mankind's past--or its future?