The Pentagon's Brain by Annie Jacobsen

Discover the definitive history of DARPA, the Defense Advanced Research Project Agency, in this Pulitzer Prize finalist from the author of the New York Times bestseller Area 51. No one has ever written the history of the Defense Department's most secret, most powerful, and most controversial military science R&D agency. In the first-ever history about the organization, New York Times bestselling author Annie Jacobsen draws on inside sources, exclusive interviews, private documents, and declassified memos to paint a picture of DARPA, or "the Pentagon's brain," from its Cold War inception in 1958 to the present.
This is the book on DARPA - a compelling narrative about this clandestine intersection of science and the American military and the often frightening results.