Perhaps the most interesting thing about Chris Pavone’s The Expats” is that his offbeat spy story has become that rarity — a first novel on its way to major commercial success.

Here’s some background: Pavone spent two decades in New York publishing, but when his wife took a job in Luxembourg, he went along in the role of househusband. His new life somehow inspired — such are the mysteries of the imagination — this novel about a bored American wife in Europe who’s secretly a retired CIA assassin. Even before publication, the novel was greeted by big-time buzz: a movie deal and the kind of advertising budget that publishers rarely lavish on first-time novelists. The buzz helped it rise quickly to bestseller lists.

Is the excitement justified? Well, more or less. “The Expats” is mostly stylish, sophisticated entertainment. Sometimes it’s silly, too, but there’s a reason for that.

At the outset, Kate and Dexter are living in the District, but they move to Luxembourg for his new, high-paying job. He’s in “bank security” — protecting banks from hackers — or so he says. Kate claims to have a mundane government job, but in fact she’s spent 15 years in the CIA, first as a field operative and occasional assassin and then as an analyst at Langley. Dexter knows nothing of this. Kate married him because he was decent and dull, but in time she becomes suspicious about just what his vaguely defined job may really involve.

In Luxembourg, Kate keeps busy with their two sons, enjoys high-end shopping sprees and grows increasingly bored. She sees other bored wives having affairs, and she’s tempted, but mostly she just wishes Dexter would help fold the laundry. Their domestic life is nicely rendered, as are the lives of other well-heeled, self-satisfied expats, and when the author sends the family buzzing about Europe, his descriptions of its many glories are gorgeous.

Kate and Dexter become friendly with an attractive American couple named Bill and Julia. Sexy Bill soon comes on to Kate, but her CIA instincts take over: She is suspicious of them both. She even fears they may be assassins, perhaps sent after her in revenge for her work for the CIA. Or might they be eyeing dull Dexter and his mysterious bank job?

Alas, this sophisticated tale stumbles when Pavone involves Kate in increasingly improbable acts of derring-do. First, she risks her life to break into Bill’s office: “Kate stood on the nine-inch-wide ledge in the rain, clinging to the side of the building, three stories above the ground.” Later, in Amsterdam, Kate’s search for a gun takes her into a brothel where two thugs are cavorting with naked women and cocaine. When she asks about buying a gun, they accuse her of being a cop wearing a wire and demand that she take off her clothes. Soon our girl is “wearing nothing except boots and underwear.” The thugs, of course, are awed. All this may make a dynamite scene for the movie, but in terms of what a real CIA agent — or any rational woman — would do, it’s preposterous. Other colorful, unlikely episodes follow.

But what standards should apply here? When I read a spy novel, it’s my instinct to compare it with the work of writers who try hard to show us the realities of the espionage game, but that’s not what Pavone is up to. Kate’s escapades are closer to Nancy Drew than to John le Carre. Think of her as a female James Bond: Realism is not the goal. But it’s those fantasy scenes of fearless Kate as secret agent — teetering on the ledge, stripping in the brothel, slugging it out with another woman — that account for the book’s success. In commercial fiction, fanciful thrills trump boring old logic every time, and fine writing, while permitted, is not really the point.

It helps that the novel ends strongly, as the long-delayed secrets of all four main characters come tumbling out. Most readers will put the book aside satisfied and probably with fond feelings for intrepid Kate. She’s no Lisbeth Salander; she’s a proper lady as action hero, sporting pearls, Prada and Jimmy Choo along with her hidden Beretta, and some women may find it more pleasing to identify with her than with a scruffy punk with multiple piercings and a dragon tattoo.

Anderson regularly reviews mysteries and thrillers for Book World.

The Expats

By Chris Pavone

Crown. 327 pp. $26