Hoffa, for his part, inhabited a universe all his own. Chuckie remembers him as pragmatic, dedicated and ruthless. If employers were hiring mobsters to be heavies in labor disputes, the union would do the same. “Twenty years ago the employers had all the hoodlums working for them as strikebreakers,” Hoffa told a reporter in 1959. “Now we’ve got a few, and everybody’s screaming.”

Goldsmith covers Bobby Kennedy’s scorched-earth campaign against Hoffa, first waged when Kennedy was the chief counsel for a Senate subcommittee on investigations and then when he became attorney general. Goldsmith concludes that Kennedy “neglected, elided or interpreted away ethical and legal restrictions” that are supposed to constrain law enforcement, sweeping up lots of “unguarded conversations” with illegal bugs.

“The same techniques could be used to destroy just about any citizen who draws the ire of the state,” Goldsmith writes, drawing a connection between Kennedy’s aggressive pursuit of Hoffa and the former attorney general John Ashcroft’s aggressive pursuit of Islamist terrorists after 9/11.

Hoffa went to prison and later made even more enemies; he had to give up labor organizing as a condition of his release in 1971, and so he started talking indiscreetly about the Mafia, which preferred Hoffa’s more passive successor. Nobody was ever charged with the eventual kidnapping of Hoffa, but the F.B.I.’s theory was that Chuckie — maybe even unwittingly — drove Hoffa to his killers.

Goldsmith works hard to try to find out what happened, poring over F.B.I. transcripts, meeting with agents who investigated the case and pushing Chuckie to say what he knows — and he seems to know more than he says. “Jack, I tell you different stories to try to avoid the true meaning.”

“In Hoffa’s Shadow” covers a lot of ground, but I was most struck by the frankness with which a buttoned-up Goldsmith writes about his stepfather, and how Goldsmith’s firsthand experiences have apparently encouraged him to question some of the surveillance powers that other law-and-order conservatives have traditionally taken for granted. (Not that he could be considered even remotely radical; just read his posts at Lawfare, the blog he co-founded, where he writes as a diligent proponent of establishment institutions.)

In the early 1960s, while Hoffa and Bobby Kennedy were at each other’s throats, Chuckie distributed thousands of copies of George Orwell’s “1984” to union locals at Hoffa’s request. It was a showboating move, for sure, and Hoffa was “an improbable defender of the American Constitution,” Goldsmith writes, but just because Hoffa’s talk of civil liberties was conspicuously self-serving doesn’t mean he was wrong. “Mr. Hoffa wanted them to read that book,” Chuckie recalls, “and said that this is what’s going to happen to not only us but to everybody — and exactly what he’s predicted has happened.”