Jonathan Dee’s trim new book arrives — like the handsome characters he writes about — burdened with high expectations. A winner of fellowships from the National Endowment for the Arts and the Guggenheim Foundation, a writer for Harper’s and the New York Times Magazine, he’s also the author of five earlier well-received novels. His most recent,“The Privileges,” was a finalist for the 2011 Pulitzer Prize. And his editor promises that “A Thousand Pardons” is “even more exciting . . . even better than the last” — the sort of well-meaning hyperbole that tempts the gods.

The opening of “A Thousand Pardons” is, in fact, instantly absorbing. When you meet Helen and Ben Armstead in a quiet suburb outside of New York, so many stress fractures are spidering across the surface of their marriage that you’ll want to shield your eyes. Ben’s untreated depression has rendered him “perfectly capable, these days, of sitting on the bed in his shorts with his lips moving silently for half an hour or more.” Without any awareness of how hurtful he sounds, he whines to Helen that his life has grown intolerably dull. Coming home every night from his law office is like a “death sentence,” he tells her. “No offense.”

Dee doesn’t mock Ben’s self-absorption, but he doesn’t forgive him for being so narcissistic, either. And by focusing on Helen’s tightly wound concern and anger, he conveys with visceral sympathy the collateral damage of depression.

Quick shifts in tone and point of view as their shiny marriage shatters make these opening pages irresistible. We cringe through the Armsteads’ final session of marriage counseling; we recoil as Ben flirts with an attractive young lawyer in his office; we wince as Ben finally runs his blessed life into a ditch. Twenty pages in, he’s disgraced and unemployed, throwing his wife and their 12-year-old daughter into financial chaos.

But unfortunately, the trajectory of this propulsive first chapter quickly droops. The novel’s sharp tone goes flat; its psychological insight turns obvious.

’A Thousand Pardons’ by Jonathan Dee (Random House. 214 pp. $26). (Random House)

Trouble starts as soon as Helen heads into the city to find employment: a 43-year-old woman with “the résuméof someone who has spent the last ten or fifteen years raising a family.” Although she’s intimidated by how young and fit everyone around her looks, she manages to land a job at a moribund three-person PR firm that burnishes the reputations of local businesses.

She has no experience with such work, but she has “an extraordinary gift,” a colleague claims. She’s honest and direct, and she has a way of disarming conflicts and making angry men apologize and thereby restore their reputations. “That is the only play,” she tells her clients. “To ask forgiveness. . . .You have to be sincere.”

One unlikely PR triumph quickly follows another until the owner of the sixth-largest PR firm in the world walks down to her little hole-in-the-wall office and hires her. “Can it really be this simple?” she wonders.

Well, no.

We’re willing to tolerate such quirky businesses in, say, the model-train world of Anne Tyler’s Baltimore, but in a novel set in crisply real, modern-day Manhattan, Helen’s enterprise seems silly. The dialogue is corny, the setting is sitcom fresh. We’re asked to believe that one of Helen’s first assignments at this world-famous firm is the archdiocesan sex-abuse scandal. But why not? Look at the way she repaired the reputation of that Chinese takeout stand . . .

Dee has written about the advertising industry before. The themes of image and essence, pretense and sincerity, run through his novels. But he’s coasting here. Serious literary fiction demands capturing the way certain kinds of work shape our lives and our thoughts. The intricacies of various professions are the stuff of affecting novels, as Richard Ford, Tom Wolfe and Jane Smiley have shown.

In “A Thousand Pardons,” Dee tries to have it both ways: a serious novel about a woman reinventing her life set in a PR firm drawn with broad, unsophisticated strokes. If this situation were played for laughs, we’d be having a different conversation but presented like this, it’s merely flaccid and implausible.

That discordant tone rattles along through the rest of the novel. A separate story line involving a handsome movie star in an existential crisis runs parallel to Ben and Helen’s marriage troubles until the plots predictably cross.

Hamilton Barth is so famous that he never has a moment’s rest from fawning fans. His public won’t let him be real, won’t let him be himself. But again, “A Thousand Pardons” isn’t sharp enough to treat Hamilton’s pampered ennui satirically, nor is it sensitive enough to make him truly sympathetic. And so we’re forced to swallow such precious cris de coeur as: “I have to live here because it reminds me every day of who I am” or “At his core he was nobody, and his nobodyness felt like something unforgivable.” If he keeps this up, Hamilton Barth can just bore the paparazzi away.

Remarkably, in the final 50 pages, this brief novel makes another chaotic lurch, this time into the realm of psychological thriller. But the murder mystery that tries to germinate here never develops any real excitement.

Is Dee experimenting with this awkward cluster of tones and styles? Did his eager publisher push him to produce another novel too soon? Fans will pardon him. Newcomers should get hold of “The Privileges” and let this one pass.

Charles is the fiction editor of The Washington Post. You can follow him: @RonCharles.

A THOUSAND PARDONS

By Jonathan Dee

Random House. 214 pp. $26