Probably the best-known fictional gun expert is former Marine sniper Bob Lee Swagger, hero of a dozen thrillers written by Stephen Hunter, former movie critic for The Washington Post. And certainly the best-known gun crime in history is the assassination of President John F. Kennedy in Dallas on Nov. 22, 1963. Surely it was only a matter of time before Hunter brought his hero to that grassy knoll.

In his latest book, “The Third Bullet,” Swagger, at age 66 and 50 years after the fact, finally gets around to investigating the JFK assassination.

Hunter is extremely well-versed on guns and ballistics, and Swagger is nothing short of a legend, a man “preceded by myth, isolated by reputation, and cloaked in diffidence.” As the novel opens, he’s spending his days quietly in middle-of-nowhere Idaho with his family, retired from trouble and hoping trouble is retired from him.

It isn’t (where would the thriller industry be if trouble ever left people alone?). While nursing his morning coffee at his favorite highway truck stop, Swagger is approached by the widow of a suspiciously Hunteresque thriller-writer named James Aptapton (you can work out the anagram on your own — it should take about four seconds), who was researching a new book when he was killed by an apparent hit-and-run. His wife thinks it was murder. The subject of the book? The JFK assassination, of course. The grieving widow presents her husband’s sketchy research to Swagger and asks him one simple question: “Is it anything?”

He thinks it is. He agrees to investigate and goes to Dallas, where an old friend in charge of the FBI field office warns him that he’s not to engage in any “cowboy” stuff, that he’s to play by the rules, etc. Since Swagger is a thriller hero, there’s no chance he’ll comply, but the warnings are a polite necessity, like calorie-listings on a boxed chocolate cake.

”The Third Bullet” by Stephen Hunter. (Simon & Schuster)

The problem is one of focus. Once Swagger starts digging into “all that Oliver Stone stuff,” he finds it difficult to separate what’s important from background noise. “How could you think about this thing at all with all the crap around it?” he wonders, but with the help of a local assassination buff, he keeps trying. When it comes to the JFK assassination, he knows that “no matter how you enter it, you get lost in the maze,” but he’s coming at it purely from the perspective of a gun expert, and he’s hoping that will clarify things for him (if not for Hunter’s readers, who’ll encounter cryptic phrases such as “the knurl-index click system of the M1 peep sight”).

Swagger possesses “a melancholy fund of knowledge on what bullets did to bodies,” and he quickly focuses on the “third bullet” of the book’s title, the final and fatal head shot that killed Kennedy. Among the facts that “all had come to believe and accept,” Swagger includes the statement that this bullet “appears to have disintegrated or detonated, as the few traces of its existence are controversial at best.”

Historians will find this puzzling — the bullet didn’t “disintegrate,” it splintered on impact, and the fragments didn’t “detonate,” they littered the floor of the limo — but it’ll be catnip to conspiracy-minded readers, as will practically everything else in this taut, efficient yarn. “Nobody wants the key moment of the late twentieth century turning on nothing more than a nobody loser’s one stroke of luck,” Swagger reflects, and there’s no danger of that happening here: Plots and counterplots take our aging, limping hero to Russia and back through a hail of gunfire. The whole thing ends with a shootout in rural Connecticut that’s so tense you’ll burn your dinner rather than stop reading.

“Are we to believe, then, that the second gunman simply vanished into thin air?” asks Vincent Bugliosi in his mammoth tome about the assassination, “Reclaiming History.” “Not only he himself, but all evidence of his existence? Is that life in the real world?” Maybe not, but it’s certainly life in the world of Bob Lee Swagger, and Hunter’s readers will be very happy to spend some time there.

Donoghue is managing editor of the online magazine Open Letters Monthly.


By Stephen Hunter

Simon & Schuster. 485 pp. $26.99