Now here’s something you don’t come across every day: a mash-up of a Western, a serial-killer mystery and a feminist-inflected tale of life in a bordello. But Jane Smiley’s “A Dangerous Business” is all that — and, amazingly, it works.

The novel is set in the wide-open town of Monterey, Calif., in 1852. Heroine Eliza Ripple (formerly Cargill) is a recent widow. Back home in Kalamazoo a few years earlier, the teenage Eliza was pushed into marriage by her parents, who were dazzled by the social and financial credentials of a handsome stranger in town named Peter.

Predictably, Peter turned out to be a con man — and one who was sexually brutish to Eliza, to boot. Entranced by the mirage of the Gold Rush, Peter dragged Eliza to Monterey, where he was promptly shot in a bar fight. Eliza didn’t shed many tears. Indeed, widowhood improved her personal and financial situation: “She was now earning her living (and a good living!) in Monterey.”

Eliza’s new place of employment is a bordello run by a Mrs. Parks, one of many such establishments in boomtown Monterey where there were “perhaps eight or nine fellows for every woman — and everyone got along well enough.”

Not since Miss Kitty of “Gunsmoke” hosted Marshal Dillon, Chester and Doc every night at the Long Branch Saloon in Dodge City has life in a bawdy house seemed so amiable. (Surely you didn’t think Miss Kitty and her “girls” were just serving up beers to all those cowpokes, did you?)

But the atmosphere shifts from risque to downright risky after two young women from rival establishments go missing and other unsettling discoveries in and around Monterey come to light. Mrs. Parks exudes the world-weary wisdom of a woman who’s been around the block a few times. “Between you and me,” she tells Eliza, “being a woman is a dangerous business, and don’t let anyone tell you otherwise.”

Around the same time, Eliza is befriended by another young woman named Jean who proffers her services at the Pearly Gates, a bordello that “attend(s) to the needs of ladies, not men.” Jean sometimes wears men’s clothes and avails herself of male privileges, taking Eliza on long walks down to the docks and into the surrounding woodlands. She also introduces Eliza to Edgar Allan Poe’s detective stories, starting with “The Murders in the Rue Morgue.”

Thinking about the deductive mastery of Poe’s detective, Auguste Dupin, “Eliza ... was impressed mostly by the idea that a train of logic could lead to something utterly unexpected.” Soon enough, Eliza and Jean will be emulating Monsieur Dupin as they take it upon themselves to investigate the mystery of the missing girls — a mystery the male authorities in Monterey are content to ignore.

Throughout her long career, Smiley (whose novel “A Thousand Acres” won a Pulitzer in 1992) has been a shape shifter, challenging herself to write in myriad literary genres. Her fiction has taken the form of academic satire (“Moo”) and speculative Norse history (“The Greenlanders”); she’s written young-adult novels and a biography of Charles Dickens, among other nonfiction. Smiley has even tackled this period in American history before, in her novel “The All-True Travels and Adventures of Lidie Newton,” set in the Kansas territory.

In “A Dangerous Business,” Smiley smoothly melds three distinct narratives into one without breaking a sweat. (There’s plenty of sweat involved, however, in Eliza’s working nights at Mrs. Parks’s establishment, where the phrase “he wanted to do his business” discreetly covers myriad erotic encounters.)

The solution to the serial killings of other prostitutes, as in Poe’s tales, indeed turns out to be “utterly unexpected”; but it’s really Eliza’s story — the adventures of a resourceful young woman stranded at the edge of the Pacific who is determined to hold onto her newfound autonomy — that commands attention.

Even though the ghastly goings-on in Monterey awaken Eliza to the ease with which women without connections can vanish, she’s determined not to return to Kalamazoo. In true pioneer tradition, Eliza has faith that whatever lies ahead has to be preferable to what came before.