The world of modern eavesdropping, or signals intelligence ... for many years ... operated in the shadows. The Puzzle Palace, the 1983 best seller by James Bamford that remains the benchmark study of the N.S.A., first pulled back the curtain to provide a glint of unwanted sunlight on the place. As each operation has come to light, an anxious public has wanted to know whether this powerful new surveillance model was undermining traditional notions of privacy and civil liberties. Just whom is the government watching? And who is watching the watchers? It has been left to outsiders - journalists, authors, civil rights advocates and privacy groups - to keep tabs on the watchers and to bring public scrutiny to once-secret programs. For the spymasters, this spotlight was decidedly unwelcome. Mike McConnell, a director of intelligence in the Bush administration, ... is one of the recurring characters in The Watchers: The Rise of America's Surveillance State by Shane Harris. Mr. Harris, with some success, does what Mr. McConnell and others in the intelligence world have found so objectionable: he watches the watchers. At its best The Watchers provides an insightful glimpse into how Washington works and how ideas are marketed and sold in the back rooms of power, whether the product being peddled is widgets or a radical model for intelligence gathering.