From the outset, Hynek and Vallee make their position clear: UFOs represent an unknown but real phenomenon. The far-reaching implications take us to the very edge of what we consider known and real in our physical environment. Perhaps, say the authors, UFOs signal the existence of a domain of nature as yet totally unexplored. In this mind-stretching book, the authors sample UFO reports, including those allegedly involving humanoids, and describe the perceived patterns in the behavior of the phenomenon. They also establish a framework for further study. Where might such study lead? What can be studied, and how? What is the real nature of the UFO phenomenon? Does it originate with the actions of other intelligences in the universe? If so, where and what might they be? Does the UFO phenomenon have a purely physical explanation, or is there a vast, hidden realm that holds the solution? In this invaluable work, we gain insight into the thinking of Hynek and Vallee’s research and investigations into UFOs, including Project Blue Book, the Pascagoula case, and the Betty and Barney Hill experience