Sue Miller’s thoughtful, intense novels have always demonstrated that domestic fiction needn’t be domesticated. And lately, she’s shown that it needn’t be apolitical either. In “The Senator’s Wife” (2008), she explored the costs of being married to a philandering public servant. Her last book, “The Lake Shore Limited,” offered a psychologically profound response to the attacks of Sept. 11, 2001.

Her new novel, “The Arsonist,” takes place far removed from national news or world conflicts, but it, too, reflects the most urgent matters of our time. In New Hampshire, where antique farms are separated by lichen-covered stone walls, she sets a muted story of class and terrorism. The result is an ambitious, big-issue novel that somehow fits convincingly amid two-lane roads and dairy cows.

This remote setting has drawn the heroine, Frankie Rowley, home from Africa. After 15 years, she’s exhausted by the moral calculus of relief work and brokenhearted by the end of a relationship with a married man. Craving time to recalibrate her life, Frankie imagines she’ll enjoy “an easy and very American happiness”: eating long meals with her retired parents and sleeping late in the bedroom “she’d had every summer since she was a child.”

But in the first paragraph, Miller begins to thwart those pastoral expectations. Jet-lagged from the transatlantic flight, Frankie takes a walk in the night and happens to see a car — what she thinks of later as the getaway car. The next morning, she and her parents learn that a neighboring house has been gutted by fire. And it’s just the first one. Over the summer, an arsonist incinerates more than a dozen houses in this small town — “a curious crime” — burning away a sense of tranquility and trust along with buildings and furniture.

Novels about kidnapped children or killer viruses may provoke some general low-level anxiety, but nothing will stoke terror in the hearts of wealthy, East Coast readers quite like this plot: It doesn’t take long for the residents of Miller’s Pomeroy, N.H., to realize that all the destroyed homes belong to summer people — tony visitors who take up lots of space in town for three months (and probably like to read sophisticated literary novels).

"The Arsonist" by Sue Miller. (Knopf)

Miller isn’t dogmatic on this theme, and she ultimately leaves it unresolved, but she’s interested in the friction between modest folks who maintain the town and “chatty, self-assured summer people” who expect it to remain an accommodating setting for their leisure. The fires force everyone to consider “who owned the town and who merely used it.” Advised to put locks on the doors, one offended visitor says, “This is not why we come here.” Miller adds, “There was something threatening in this tonally, inflectively, as if to say, If you can’t manage this better, we won’t come here anymore.”

At a time when even mentioning the widening distance between the classes is considered an act of class warfare, it’s encouraging to watch Miller’s novel negotiate this awkward fact of American life. An older character in town who serves as a kind of sage offers a counterintuitive explanation for the fires — and the resentment that may be fueling them: “That expectation that we’ll all get along — that didn’t use to matter so much,” he says. “Because there was no such expectation. There was no social mixing. . . . We knew our place.” In other words, our pretense of egalitarianism is destined to aggravate tensions between groups that live very different lives.

That argument is complicated, though, by Frankie’s point of view. After years of working in some of the most desperate parts of Africa, she finds America a vast expanse of prosperity. “It all seemed criminally luxurious,” Miller writes. Tensions between townies and summer people in “this little, closed-in world” look silly after watching children die of starvation. But how long can Frankie burn with that bright blue flame of moral superiority? It’s a privilege, after all, to be able to obsess righteously about Big Important Problems. At 43, she’s begun to realize that her devotion to the fathomless crises of Africa serves as a kind of cowardly escape. Forced by a friend to articulate her restlessness, Frankie sputters, “I guess, I’ve come to feel — in Africa — that I’m . . . temporizing, I guess you could say. With my life.”

Even while the arsonist keeps striking in the background of this novel, we’re caught up in Frankie’s experiment with stability. Soon after she arrives home, she falls in love with Bud, the owner of the local newspaper. A transplant from the Washington bureau of the Boston Globe, Bud is a solid, immensely likable guy, but he, too, is wrestling with a sense of being suspended between worlds, and it’s not clear that he’ll be able to convince Frankie that a worthwhile life can be lived in the narrow confines of Pomeroy.

Miller has taken heat in the past for embellishing her stories with sweaty prose, and there are moments here when the romance feels hotter than the mystery, e.g.,“Frankie felt a weakness in her legs at the thought of everything they would do with each other, to each other, at the way in which their bodies belonged to each other.” But for the most part, Frankie’s relationship with Bud, which serves as the real focus of the story, is thoughtfully and maturely explored. There’s humor and real sweetness in this clumsy slow-dance of middle-aged dating.

Most affecting, though, is the portrayal of Frankie’s parents. Once again, as Miller did in “The Lake Shore Limited,” she explores the way illness strains a relationship and exposes cracks that happier times kept hidden. As Frankie’s father drifts further into dementia, her mother realizes that her loveless marriage is becoming a different kind of prison — one constructed of burden and guilt. And Frankie must figure out the ways her parents still need her, and don’t.

Set against the acts of a serial arsonist, which, in turn, are set against the attacks of African terrorists, these ordinary folks’ hopes and fears could seem small and petty, the kindling for some bitter satire about American self-absorption. But that’s the continuing miracle of Miller’s compelling storytelling: She knows these people matter, and as she moves gently from one character’s perspective to another, her sensitive delineation of their lives convinces us of that, too.

Charles is the editor of Book World. His reviews appear every Wednesday in Style. You can follow him on Twitter: @RonCharles.