The Argentinean author Ariana Harwicz writes slim books that draw on a slim band of resources, as if she pulled them from a narrow row of diseased crops, or from the soil atop a shallow grave. Her composite antihero is a mother gone mad in a rural village in France. There are flies in the folds of her kitchen curtains, probably, and a machete left out on the lawn. She is besieged on all sides—by her in-laws, by social workers, by untreated psychosis—and yet in possession of a terrible freedom. She wishes she were dead, but she’s inclined toward killing someone else first. She is overwhelmed by anger and lust, an alchemical compound that can alter matter, energy, laws of physics. Characters teleport, rewind themselves—the reader is often unsure of where she is in time and space—and traverse the boundaries between species. In Harwicz’s “Die, My Love,” the unravelling protagonist’s lover presents as “a crazy fox on the roadside”; after she sleeps with him, she expects to “have a beak, feathers, talons.” Her superego, or maybe her id, keeps materializing in the form of a stag, and she sees her baby through the eyes of a crab. The narrator of Harwicz’s “Feebleminded” describes her brain as “moths in a jar, hanging themselves.” The opening line of another novel, “Tender,” is “I wake up gaping like a force-fed duck when they strip its liver out to make foie gras.”

“Die, My Love,” which was long-listed for the 2018 International Booker Prize and has been adapted into an upcoming film starring Jennifer Lawrence and Robert Pattinson, is Harwicz’s best-known work. It can be fairly categorized as a work of postpartum psychological horror, a transatlantic cousin to Rachel Yoder’s “Nightbitch,” in which the tensile stress between thwarted professional ambition and maternal longing starts to turn a woman into a dog, or to the title story of Karen Russell’s collection “Orange World,” wherein an anxious, sleep-deprived new mother comes to the conclusion that she is breastfeeding Satan. These are essentially gothic works, in which bleary, nocturnal isolation opens a door to bizarre impulses and uncanny transformations.

Harwicz’s novels are more hallucinatory than supernatural—but a more provocative distinction between her books and others in this semi-subgenre is that, for her characters, motherhood does not cause animal rage and instability so much as instantiate them. At one point in “Die, My Love,” the unnamed protagonist sits back and watches as her baby crawls toward a fireplace and burns his hands; at another, she sticks crackers in his mouth until he chokes. She was always like this, one suspects, only now she has a kid. “Mummy was happy before the baby came,” she muses. That’s an unreliable narrator.

“Unfit,” Harwicz’s latest novella to appear in English, was published in Spanish last year as “Perder el Juicio,” which carries the double meaning of losing one’s mind and losing one’s case. The unhinged narrator, Lisa, is, like Harwicz herself, a Jewish Argentinean woman living in a small French village. She has been accused of domestic violence—the details are left hazy—involving her estranged husband, Armand, who is the father of her five-year-old twin sons. Scores of eyewitnesses have come out against her, Lisa says, but these are “fake resistance fighters, informing on collaborators, collaborators passing themselves off as heroes.” Armand and his parents have custody of the twins, whom Lisa can see for supervised visits just once a month, “even less than terrorists’ families,” she complains.

No one is on Lisa’s side in what she perceives as a literal war, especially not her antisemitic in-laws, whom she imagines speculating about the so-called Israelite among them: “I’ve heard they wear wigs and never wash their private parts, that they smell like cooking oil.” Despite a restraining order against her, Lisa skulks around the twins’ school at drop-off and stalks them in the grocery store. She wants them back seemingly less out of primal longing and more out of spite, or out of umbrage that she’s been robbed of her rightful possessions. Almost on impulse, Lisa sets fire to the house and yard adjacent to where Armand and the boys are staying with the in-laws; the conflagration lures the adults from their home—“like rats from their hidden den,” Lisa thinks—and gives her the chance to steal into the main house and reclaim her boys. A road trip ensues, sort of, albeit one in which the reader is not always clear on who’s inside or outside the car.

All of Harwicz’s novels unfold at a sprint and feel at ease with narrative ambiguity and spatial confusion. But “Unfit,” which is translated, from the Spanish, by Jessie Mendez Sayer, feels especially rushed and patchy with elisions. These tendencies are most consequential in the kidnapping scene, a gnarled set piece that, in its planning and execution, seems to defy even dream logic. The vagueness and disorientation are plausibly by design, meant to evoke the fracturing of Lisa’s sanity, perhaps. How much the reader should sympathize with Lisa—whether the character whom Harwicz has created is more aptly seen as a wronged person lashing out or as a more lucid villain—also feels unresolved.

Like many of Harwicz’s characters, Lisa is a zealot of sorts—and an avatar of the author’s unusual belief in the value and importance of hatred. “This era, in literary terms, does not know how to hate,” Harwicz wrote, on X, last year. In her books, anything that smacks of compassion or tenderness deserves, at best, strategic suspicion. “Love is bribery in the plain light of day,” Lisa says, “a padlocked emergency exit, fireworks aimed at the sky.” Love is a show of virtue, a branding exercise, a cynical transaction. Love is commerce; hate is art.

Harwicz has told interviewers that “Unfit” has echoes of her own divorce proceedings, during which she says she faced sexist and antisemitic discrimination, and of the case of Sofía Troszynski, an Argentinean woman who fought an international custody battle with her French-born husband over their toddler daughter; mother and child later disappeared. It also seems significant that Harwicz was in the last months of completing the manuscript for “Unfit” on October 7, 2023, when Hamas launched its brutal attack on Israel—a cataclysm that, according to Harwicz, reconfigured her sense of her place in the world. “If I had to write my biography—my invented life, another book of fiction—I would start with October 7th,” Harwicz has said.

Even a reader who was unfamiliar with that comment might think of the events of October 7th when reading “Unfit,” particularly during the passage describing Lisa’s kidnapping of her sons. As she carries her sleeping boys to her car, one and then the other, she imagines “rescuing bodies from an ambush by fanatics.” She speeds away from the scene, but, in her mind, the ambush is still under way: if “I heard the fanatics coming,” she thinks, “I would hide underneath other bodies.” She drives past ditches that “are filled with the metal skeletons of burned-out, abandoned cars,” and looks forward to the boys waking up so that they can celebrate a “successful hostage exchange.” She imagines candlelight vigils and frantic searches through charred rubble, and imagines digging tunnels. She sees missing-person posters. When she argues with Armand on the phone—Harwicz does not clearly signpost who is saying what—one spouse warns that the other will “soon understand the legitimate right to self-defense.”