Our Haunted Planet by John A. Keel

A provocative survey of UFOs, poltergeist cases, phantom people and other unexplained phenomena that argues these disparate reports are manifestations of a single, persistent and often deceptive intelligence operating on or within the planet; the book compiles worldwide case studies, eyewitness testimony and historical parallels to suggest that what people call aliens, ghosts or strange apparitions may be different faces of the same high-strangeness phenomenon, capable of manipulating perception, fabricating physical effects and exploiting cultural expectations, and it advances speculative hypotheses about the nature and purpose of this force rather than offering conventional extraterrestrial explanations.