This book is the first in-depth, authoritative look at the flying saucer phenomenon and is considered to this day to be one of the best books on the subject ever written. Extremely well researched work with facts that were documented, containing none of the disinformation and hype that has crept into the field over time. The author was a retired Marine Corps Major who became an aviation writer, and was therefore perfect for the job of researching and writing this book. Using his own knowledge and information from friends in the military, Keyhoe came to the conclusion that UFOs originate from outer space and the U.S. military was engaged in a cover-up. He includes a number of documented cases whereby thousands of people witnessed strange objects in the sky all at the same time, in various parts of the country. Eyewitnesses are interviewed and much is done to show how and why the veil of government secrecy was enforced.