In his own lifetime, which began in 1888 and ended in 1959, Raymond Chandler was more private even than his incorruptible private detective, Philip Marlowe. Since then, however, Chandler’s mean streets have been shadowed by biographers — Frank MacShane, in “The Life of Raymond Chandler” (1976), Tom Hiney, in “Raymond Chandler” (1997) — hagiographers, and even photographers — “Raymond Chandler’s Los Angeles” with text by Elizabeth Ward and photos by Alain Silver (1987). His letters and interviews have been collected, his association with Hollywood scrutinized — “Raymond Chandler and Film” by William Luhr (1982) — and his wastebaskets picked through — “The Notebooks of Raymond Chandler,” edited by Frank McShane (1976).

You wouldn’t think there would be any clues left that the literary gumshoes haven’t already stumbled upon. But the obvious, as Holmes said to Watson, is precisely that which we overlook. In “The Long Embrace: Raymond Chandler and the Woman He Loved” (Pantheon, 368 pages, $25.95), novelist Judith Freeman (“Red Water,” “The Chinchilla Farm”) has found evidence that has been in plain sight all the while: Chandler’s strange 30-year marriage to a woman 18 years his senior, Cissy Pascal, and their peripatetic lifestyle in Los Angeles — tracked by Ms. Freeman with a doggedness that Marlowe would have admired — were defining elements of his life.

In previous books on Chandler, Cissy was always a shadowy background figure, whose presence went largely unexplained at the end of the story, and perhaps it took a woman and a novelist to bring her to the forefront. Born Pearl Eugenie Hurlbert in Ohio just five years after the end of the Civil War, Cissy apparently lived a wilder life than any of Chandler’s femme fatales, a full half-century before he wrote about them. The evidence is strong that she posed for nude photos in her youth, and she was already into her second marriage when she met Chandler, a bachelor in his late 30s who was caring for his elderly mother. She lied to him about her age, shaving a decade off her life on the marriage certificate; when they were married she was 54, and exactly when Chandler discovered the truth isn’t clear.

Ms. Freeman makes ingenious connections between the details of Cissy’s life and her husband’s books — for instance, both the nude photos and her increasing use of drugs appear in the cloud of vice that hangs over the plot of “The Big Sleep.” Ms. Freeman makes an even stronger case that many of the chivalrous elements of Marlowe’s character developed in the hothouse of their marriage: “It was Ray’s job to take care of a needy, vulnerable woman,” she writes, and his devotion to her helped to create “the sense he had of himself as her white knight” — precisely the phrase so many used to describe Philip Marlowe. Despite their age difference, James A. Cain thought them “Hollywood’s happiest couple,” at least before Cissy’s illnesses kept them confined to home, and after her death, Chandler would describe their marriage as “almost perfect.” (He burned several of their letters just before his death, telling an English publisher, “Some of the letters to my wife are pretty hot.”)

“The Long Embrace” suggests a startling alternative possibility, that Chandler spent his life denying latent homosexuality. The whiff of same-sex attraction hangs over one pre-Marlowe story, “Pearls Are a Nuisance,” “like a cloud of cheap aftershave,” Ms. Freeman writes, as it does from other stories in the period. One of the main characters, Walter Gage, “speaks ‘like Jane Austen writes,’ and when he talks he waves an ‘airy hand.'” Another character, the rough-talking Henry, says to Walter, “don’t pansy up on me.” The two wind up in bed together in their underwear, passed out: “There were garments lying here and there on the floor … “

Those of us fixated on Chandler’s women never quite noticed, as Ms. Freeman does, that “‘Not getting the girl’ in Marlowe’s case is never really a misfortune because it’s never really a goal … for Marlowe, a warm erotic feeling towards a woman never seems a possibility.” The exception was Anne Riordan in “Farewell, My Lovely,” “whom he declines to sleep with on moral principle” (and who was, like Cissy, a redhead).

It would have been easy for Ms. Freeman to fixate on the subject of Chandler’s sexuality or, by only referring to his work, label him as a misogynist or homophobe. (Marlowe, like Hammett’s Sam Spade, liked to rough up “pansies.”) And there is clear evidence for the homophobia: Ms. Freeman quotes from a 1957 letter from Chandler to his English solicitor: “I rather disagree with you that they can not be judged … These are sick people who try to conceal their sickness … they just make me sick. I can’t help it. My dead wife could spot one entering a room. Highly sexed women invariably seem to have that reaction.”

“Had Cissy really had such an aversion to homosexuals?” Ms. Freeman asks rhetorically, or “Did she sense the threat they might present to her?” Stephen Spender’s wife, Natasha, told Ms. Freeman that she and a group of her close woman friends “Simply assumed [Chandler] was a closet homosexual.” “The one thing I knew for certain,” Ms. Freeman concludes, “was that he had adored women all his life. He had worshipped his wife.” Such devotion covers a multitude of personal sins, but it was Chandler’s devotion to the figure of the solitary male that produced his major achievements as a writer.

“The Long Embrace” isn’t a critical biography, and Ms. Freeman can be forgiven for not being able to explain how a fatherless boy educated at Dulwich school, and later an oil company executive fired for alcoholism who didn’t become a success until well into middle age, could have had such an enormous impact on both popular and high culture.

Indeed, Chandler took a circuitous route to prominence. He was 51 when he published his first novel, “The Big Sleep,” in 1939; of the other six novels, “Farewell, My Lovely” (1940) and “The Lady in the Lake” (1943) are generally regarded as the best. There isn’t much more that one could call essential work, just a couple of volumes of stories, a few essays (one of which, “The Simple Art of Murder,” gave the world the phrase “mean streets”), and two film scripts, Billy Wilder’s “Double Indemnity” (1944) and Alfred Hitchcock’s “Strangers on a Train” (1951). The first was a collaboration with the director, while judging from Chandler’s bitter letters to Hitchcock, the second was considerably rewritten.

From that handful of slim volumes, a literary genre was spawned that has mutated and evolved, from film noir in the late 1940s to graphic novels in this century. A very good case could be made that Raymond Chandler has had more impact on both serious and popular culture with his handful of works than any other American writer, and his influence extends even overseas. Chandler has been lauded by Auden, admired by Camus, and dismissed by Borges. (“The atmosphere in these stories,” Borges sniffed about Chandler and Dashiell Hammett in his “Lectures on American Literature,” “is disagreeable.”) He has inspired fiction both low — Mickey Spillane’s Mike Hammer, whom Chandler loathed — and high — Haruki Murakami, who told an interviewer a few years ago, “Philip Marlowe is Chandler’s fantasy, but he’s real to me.” And, more than anything else, he has inspired American movies, which owe the very archetype of masculinity showcased by filmmakers as diverse as Howard Hawks and Robert Altman to Chandler and his Marlowe.

How he did this, exactly, has eluded even such devotees as Auden and Clive James. Whatever Chandler’s limitations, his work is more complex than the ideas they were supposed to be about, and the fears they expressed are more troubling than the mystery genre can contain. Ms. Freeman, I think, comes the closest to pinpointing his appeal: “What Chandler understood, and what he wrote about so well in his novels, was the fact that a new kind of American loneliness was born in L.A., in people who found themselves marooned in paradise, lonely amidst abundance and incredible wealth. Lonely in a seemingly incurable fashion … This was the loneliness Marlowe would come to embody — a haunting sense of detachment from any sense of origin, family or roots.”

Mr. Barra writes about sports for the Wall Street Journal and The New York Sun, and about books for the Sun and the Washington Post.