The proof of UFO visitations - from human anecdotes, videos and photographs to once-secret documents - is overwhelming. Mankind's historical record is replete with accounts of flying objects and unearthly visitations. Today with the widespread use of video and cameras the evidence of UFO activity gains weight almost daily. It's not limited to lights in the sky - associated activities include animal mutilations, crop circles, scrutiny of military installations and even human abductions. What is the nature of these visitors? Are they beings from another plant? Another dimension? A different time? More importantly, what are their intentions. This work aims to break through the misconceptions and conflicting theories. Focusing on some of the most respected UFO investigators and their evidence, it seeks to uncover the purpose of UFO occupants. Jim Marrs is the author of Crossfire: The Plot that Killed Kennedy.