Book by biological anthropologist Michael Masters presenting his extratempestrial hypothesis, which argues that at least some UFO occupants described in witness reports could be future humans rather than visitors from another planet. The work is framed as a multidisciplinary interpretation that draws on anthropology, anatomy, time-travel speculation, and recurring features of abduction and contact narratives. Released in 2019 as an independent title, it sits in the theory-building side of the Atlas rather than the witness-testimony or archival side. Its significance here comes from offering one of the more developed contemporary alternatives to the standard extraterrestrial explanation.