Tim Weiner's new book, Enemies: A History of the F.B.I., is an outstanding piece of work. The F.B.I. ... from World War I on investigated all manner of political radicals and Communists, compiled lists of Americans to be detained in the event of national emergency and engaged in at least half a century of illegal wiretapping, mail opening and burglaries. This is certainly the most complete book we are likely to see about the F.B.I.'s intelligence-gathering operations, from Emma Goldman to Osama bin Laden. Where Mr. Weiner excels is in connecting the dots. He identifies his themes, almost all involving the conflicting demands of civil liberties and civil order - "the saga of our struggle to be both safe and free," as he puts it - and rigorously pursues them. Illegal wiretaps and burglaries were the F.B.I.'s key weapons almost from the beginning. Time and again, going back to the 1930s, this or that court would rule such procedures illegal. Time and again, J. Edgar Hoover, the bureau's director from 1924 until his death in 1972, simply ignored the law. A string of presidents, from Roosevelt to Richard M. Nixon, knew exactly what the bureau was doing and refused to stop it. Hunting Commies ... was Hoover's true life's work - the one thing, other than his reflexive bureaucratic defensiveness, that obsessed him from his first radical raids in 1919 into the 1960s.