The America imagined in Jim Crace’s new novel, “The Pesthouse” (Nan A. Talese, 255 pages, $24.95), has been ravaged first by some civilization-wrecking catastrophe long in the past and now by a “Grand Contagion” felling entire villages overnight with clouds of poisonous vapor. What remains is a wilderness inhabited by superstitious, illiterate subsistence farmers and fishers, menaced by marauders on horseback as well as “the flux,” an airborne disease that has laid the populace low and put the survivors to flight.

The novel tracks the journey, and the burgeoning love, of two of these emigrants, Franklin Lopez, a sturdy and jolly man barely past his adolescence, and Margaret, a beautiful, redheaded 31-year-old virgin. They meet in a shed in the woods called the Pesthouse, where Margaret has come to recover from a near fatal bout of the flux, and travel east to the coast to escape across the ocean — manifest destiny in reverse.

To begin a novel, as Mr. Crace does here, with the words “Everybody died” is an act of authorial aggression. To set this fictional massacre “in America” invites the charge of perversity, or at least glibness. But Mr. Crace, a Briton and the author of eight previous works of fiction, is not up to anything so banal as anti-Americanism, though he does seem to delight in teasing the reader with the notion that he might be. Rather, he has laid waste to the American landscape not out of spite but to test his powers to write his way out of it.

Along the way, Mr. Crace works within various literary modes, some more American than others. The post-apocalyptic genre, before Cormac McCarthy took it up to win the Pulitzer Prize last month for “The Road,” has primarily been the stuff of Hollywood, and the ruffians who shackle and enslave Franklin midway through “The Pesthouse” have a vaguely “Mad Max”-ish quality. Mr. Crace also deploys the old science-fiction trope of primitives discovering the relics (a penny depicting “Abraham [who] would come back to help America one day”; a pair of binoculars, here “spy pipes”) and ruins (a crumbling factory; a cracked, overgrown highway) of our society. These are disclosed at first as puzzles, and readers with little appetite for this sort of trickery may be frustrated by this novel; the rest of us will find much to delight in.

Mr. Crace indulges in a bit of Pynchonesque absurdism in an episode that sees Margaret, separated from the captive Franklin, take shelter in a boardinghouse called the Ark, run by a cult called the Finger Baptists. They are not Christians — no one in this America seems to be — but rather an ascetic order that has renounced metal, which “has brought death into the world. Rust and fire are God’s reply.” They have also given up the use of their hands; their lodgers spoon-feed and bathe them in return for room and board. The Ark makes for Margaret a pleasant reprieve, until the bandits who kidnapped Franklin arrive and in short order slay the defenseless Baptists. Here Mr. Crace’s absurdist turn slips briefly into sadism, but it also allows Margaret and Franklin a fairy-tale reunion, and it is in fairy-tale form that the couple forsake their escape and return to the Pesthouse at the novel’s end.

Whereas Mr. Crace is often called a psychological novelist, his treatment of Franklin and Margaret would be better termed instinctual. Especially in the book’s first third, it is naturalism, recalling Jack London, that animates the pair’s simple attempts to fill their stomachs. Margaret turns out to be adept at catching birds:

By the time the sun was high enough to offer some heat to the day in exchange for a little steam, Margaret had netted a fair-sized quail and a bird she could not remember seeing before, dappled brown and black but fat and edible. She broke their necks and snapped off their wings. … She split the carcasses open with Franklin’s knife. It was not easy or pleasant to pull out the bones or tug away the skin and feathers.

The novel brims with such passages, culminating in Franklin’s slaughtering a horse into steaks, and only the austere grace of Mr. Crace’s prose saves them from plunging into procedural monotony.

The narrator of “The Pesthouse” speaks with a knowingness that mocks a vein of middlebrow American storytelling that saw its apogee in Thornton Wilder’s “Our Town” and is preserved on the airwaves in the form of Garrison Keillor’s “A Prairie Home Companion.” As they first depart the Pesthouse, the narrator asks, “Were they in love? Well, no, not yet. … They were, though, getting there with every step.” Mr. Crace moves from this chatty earnestness into faux erotic details of Franklin carrying Margaret on piggyback: “And they were as intimate as lovers. How could they not be, with her legs pushed open, wrapped around his back, her breath and lips between his nape, her arms embracing him, clasped across his breastbone?”

In his teasing playfulness, Mr. Crace has something in common with the Danish filmmaker Lars von Trier, whose recent efforts “Dogville” and “Manderlay” pose as critiques of America but are intended merely to provoke as they play games that are essentially formal. “The Pesthouse,” too, is an exercise in form, and Mr. Crace’s phantom America is a rich and strange creation.

Mr. Lorentzen, an editor at Harper’s Magazine, last wrote in these pages on the novelist Thomas Mallon.