Louis Bayard is a novelist and reviewer.

‘What really knocks me out,” Holden Caulfield says, “is a book that, when you’re all done reading it, you wish the author that wrote it was a terrific friend of yours and you could call him up on the phone whenever you felt like it.”

J.D. Salinger wasn’t much for phone calls, and when admiring readers came slouching toward Cornish, N.H., seeking an audience, he did his very best to discourage them. He had a perfect hatred for photographers and reporters and critics and ex-lovers and most anybody else who failed his test of purity. Like Garbo, he wanted to be alone, and like Garbo, he made it impossible because, in one novel, he created a voice of such disarming intimacy that generations of teenage readers believed he was talking directly to them. And the more they talked back, the more he ran.

Imagine how fleetly he would fly before the spectacle of “Salinger,” an oral biography clothed in the distressed brick-red jacket of an old “Catcher in the Rye” paperback — but really just one pincer in a multimedia Anschluss that includes surgical strafings of advance press, followed by the rumbling tank of a documentary film (already “acclaimed,” according to the book’s cover, though it won’t be released until Sept. 6) and, one imagines, a carpet bombing of magazine features and book-festival appearances and morning TV and afternoon NPR.

Well, grant co-authors David Shields and Shane Salerno their moment of effulgence. Together, they have logged nine years of research, collected more than 200 interviews across five continents, disinterred lost photographs, military records and billets-doux, and even unearthed a secret cache of soon-to-be-published Salinger novels, allegedly coming sometime between 2015 and 2020.

“Salinger” by David Shields and Shane Salerno. (Simon & Schuster)

These guys are bucking for the big show. And bucking a bit too hard, if we may judge from their most prized “find”: Salinger’s undescended testicle, an “anatomical deformity” that apparently didn’t stop him from engaging in multiple affairs or fathering children but that, in the eyes of Shields and Salerno, becomes his wound of Philoctetes, shaming him into seclusion and art.

“Salinger” has some undescended elements of its own. It contains no index. Its end notes are seriously incomplete. Its passing errors (the names of author John Hersey and Larry Darrell, the hero of Maugham’s “The Razor’s Edge,” are misspelled more than once) suggest a book that has been rushed to market. The absence of connective prose tissue leaves the pages echoing with voices and countervoices and no clear way to distinguish between them.

Did I mention it’s expensive?

And now let the grumbling cease because “Salinger” is the thorny, complicated portrait that its thorny, complicated subject deserves. If nothing else, the book offers the most complete rendering yet of Salinger’s World War II service, the transformative trauma that began with the D-Day invasion and carried through the horrific Battle of Hürtgen Forest and the liberation of a Dachau subcamp. “What a tricky, dreary farce,” Salinger said after receiving a citation for valor, “and how many men are dead.”

It was more farce than he could handle. He was hospitalized for shell shock (an experience vividly dramatized in his short story “For Esmé — With Love and Squalor”). He married a German woman who may have been a Gestapo informant, then divorced her in short order and rematriculated uneasily into the Park Avenue of his childhood. Always a facile writer, he was now a serious one — personally anointed by Hemingway — and he began publishing to great acclaim in the New Yorker.

Had he stayed on that narrow track, Salinger might have gone down in literary history as a petit maître: a stylist of dry, wry tenderness, with an exceptional ear for dialogue. But for many years, he had been lugging around the kernel of a novel. (Literally lugging: The first six chapters went with him onto the beaches of Normandy.) It had nothing much in the way of plot — an expelled prep-school student wanders around Manhattan, raging against phonies — and its charms eluded Salinger’s pals at the New Yorker. But Little, Brown liked it, and when it came out in 1951, at the price of $3, it found its audience right away. And never lost it.

“The Catcher in the Rye” has sold 65 million copies worldwide, but that figure doesn’t say nearly enough. For good or ill, this is the book that recombined our cultural DNA. “It’s impossible to be an American writer now,” Rick Moody says, “and not feel the influence . . . that very personal first-person.” From “The Wild One” and “Rebel Without a Cause” to “Ferris Bueller’s Day Off” and “The Perks of Being a Wallflower,” every teen malcontent in our pop culture owes something to Holden Caulfield, his restiveness, his rancor, his conviction that the world he’s inheriting is a sham.

And no one seemed to share that conviction more than Holden’s creator. Having achieved the American dream, Salinger turned heel. He moved to New Hampshire, where he sequestered himself in a concrete bunker and wrote — day after day. He married and had a family, but the claims of his fictional families were every bit as pressing. His work grew denser, less frequent. Then, after 1965, he stopped publishing altogether. Years went by; the faithful waited; nothing came.

The authors of “Salinger” attribute this long silence to his embrace of Vedanta Hinduism, which “transformed him from a writer of fiction into a disseminator of mysticism.” Indeed, the heart of the Salinger mythos was that he was too holy, too monastic for this bitter Earth. And yet, as Shields and Salerno point out, he was very much of the world. He encouraged film adaptations of his work. (Jerry Lewis desperately wanted to play Holden.) He dated a Hollywood actress and a nationally published columnist. He watched TV and traveled and wrote copious numbers of letters. He generally shunned interviews, but at punctual intervals he made himself available to journalists, especially the pretty ones. Above all, he tended his reputation with great ferocity, reading every review, crying foul on pirated editions and suing to stop a biographer from using old letters.

Again and again, the great man’s mythos cracks open to reveal an anti-mythos. Salinger the pacifist creates, in his only novel, an alter ego so at war with humanity that the book becomes the personal Bible of assassins. (Both John Hinckley and Mark David Chapman cited its influence.) Salinger, the modern bard of childhood, neglects his children and engages in a lifelong habit of seducing young, female virgins — girls, many of them — then abandoning them as soon as the affair is consummated.

These are matters of more than prurience. Salinger’s unanchored rage, his deeply conflicted notions of innocence, are as central to his work as to his life. What makes “The Catcher in the Rye” a young-adult novel — which is to say, what limits it — is its implicit endorsement of Holden’s delusions: that children are pure, that a sweet little girl is wiser than any grown-up, that simply to grow up is to be diminished. Indeed, if anything gives that last notion the lie, it’s Salinger’s art. Holden Caulfield could never have written the story of Holden Caulfield. That could have been written only by the man who lived through Utah Beach and experienced the Holocaust firsthand. The man who spent his whole life trying to unsee what he saw.

Louis Bayard is a novelist and reviewer.