Alien experts explore the ruins of an ancient city, but they can't help noticing how well cut the stone is, how sophisticated the architecture was, and how advanced the engineering used was. Is it possible this site wasn't built by humans at all? Investigators circle the globe in search of evidence in their quest to determine whether life on Earth began in outer space and if aliens influenced mankind in ancient times. Did extraterrestrial beings visit Earth and share information about technology and influence human religions?