From New York Times bestselling author of The Only Plane in the Sky and Watergate comes the first comprehensive and eye-opening exploration of our government's decades-long quest to solve one of humanity's greatest mysteries: Are we alone in the universe?

From the post-war Project Blue Book to the Pentagon's modern-day Advanced Aerospace Threat Identification Program, historian Garrett M. Graff presents the first serious narrative history of humanity's hunt for alien life--including the military and CIA's secret, decades-long quest to study UFOs.

A thrilling story of science, the Cold War, Nazi research, atomic anxieties, secret spy planes, and the space race, UFO traces the real-life history of the US government's hunt for "unidentified aerial phenomena" here on Earth, from Roswell to Rendlesham Forest, as well as the story of the small group of forward-thinking scientists--astronomers like J. Allen Hynek, Frank Drake, Carl Sagan, and Jill Tarter--who launched the search for extraterrestrial intelligence far from Earth.

Drawing on original archival research, declassified documents, and interviews with senior intelligence and military officials, Graff's book traces the long history of our quest to understand one of the most profound and popular questions of all time: whether or not aliens exist.