Such was the question to Dan Rather, in October of 1986, when, on a street somewhere in New York City, a crazed mugger pummeled him while repeatedly asking, “What’s the frequency, Kenneth?” In 1997, Rather identified William Tager from a photograph in the New York Daily News. Tager, currently serving prison time for the killing of an NBC stagehand in 1994, seemed to have been convinced that government agents were beaming signals into his head. With a certainty that eerily echoes his defense of the faked memos in the President Bush National Guard story on 60 Minutes II, Rather said,...