The title for this documentary about Daniel Ellsberg, the defense department analyst who leaked the Pentagon Papers to the New York Times in 1971, is how Ellsberg was described at the time by Henry Kissinger, the U.S. secretary of state. Of course, back then plenty of people thought Kissinger was the most dangerous man in America, or perhaps his boss, Richard Nixon. If you wanted to be the most dangerous man in America in 1971, you really had to put in some hours.