The book's subject matter mostly concerns events in Point Pleasant, West Virginia during 1966 and 1967, focusing on sightings of a creature dubbed Mothman. It also includes Keel's theories about UFOs, Men in Black, ghosts, and other paranormal phenomena, as well as the December 5, 1967 collapse of the Silver Bridge across the Ohio River from Point Pleasant to Gallipolis, Ohio.
Throughout the book, Keel creates a reasonably coherent theory of the connection between all these events and phenomena. The veracity of the events described, especially those said to have been witnessed only by Keel himself, cannot be further established beyond reasonable doubt. However, Keel's world view and theories are certainly interesting reading, and unorthodox compared to those of most UFO and paranormal phenomena buffs.
The book was the basis of a 2002 movie by the same name, starring Richard Gere, which featured some of the same themes and accounts, but in a much more fictionalized manner. The movie received lukewarm reviews.
Book
The Mothman Prophecies, by John Keel, Saturday Review Press, 1975 and Tor Books, (paperback) 2002 ISBN 0765341972