Sentiment, though, is scarce, befitting the flinty style of Mr. Hersh, who has a knack for cycling through employers and exhausting his editors. (After a messy split with The New Yorker, he no longer has a regular venue for his work.) He knocks reporters for laziness and editors for timidity. He notes that major publications passed on his My Lai exposé, fearful of government denials that American soldiers had murdered dozens of Vietnamese civilians. In the end, Mr. Hersh syndicated the stories himself, and won a Pulitzer Prize for his efforts.

As with any Hersh production, “Reporter” has news. He recalls hearing a tip that Richard Nixon’s wife, Pat, went to the emergency room in 1974, shortly after the Nixons had left the White House, saying her husband had hit her. (Mr. Hersh writes that he made a mistake by not reporting this at the time; the Nixon family denied similar allegations of domestic abuse when they surfaced in years past.) He describes Lyndon Johnson expressing his displeasure over an article by meeting a reporter at his Texas ranch and — there is no pleasant way to put this — defecating on the ground in front of him.

He remembers a night in San Francisco during the 1968 presidential campaign, when he was working as the press secretary for Eugene McCarthy. (Yes, Mr. Hersh, the reporter’s reporter, had a stint on the public-relations side of the game.) Mr. McCarthy had never smoked pot, so Mr. Hersh produced a joint; joining the group was Jerry Brown, the future governor of California. “The stuff did little for McCarthy, so he said, but it did much more for Brown,” Mr. Hersh writes.

A spokesman for Mr. Brown, contacted for this article, called the anecdote “a complete and total fabrication.” Mr. Hersh shrugged off the denial. “omg … why is he making a big deal of it?” Mr. Hersh wrote in an email. “it was the 60s, was it not?”