In the opening pages of Liz Harmer’s smart, sharp, and magnetic novel Strange Loops, Francine revisits the past. Deeply, frantically restless (whether in her role as wife, mother, graduate student, or coffee shop proprietor), Francine shows up at her mother’s luxurious – and empty – country home five years after a ruinous weekend reunion of siblings and spouses. She recalls, “It had taken one day to bring the place to a boil. They’d all screamed at each other. In front of babies, at pregnant women, they’d all screamed.”

Present-day Francine is not alone. Having moved beyond the “unethical crush” phase, and dispensed with rationalizations (“Attraction roved around and didn’t mean a single thing”), and affected by “the contagion” of a first-year student’s hormones, this creature of passions has snuck away for a weekend of sexual bliss.

In the aftermath, any reader will correctly surmise, tears will be the least worry.

In Harmer’s deft telling, Francine is a riveting figure, a tempest of attractions and moods. After a few hours, even the titillating student fails to bewitch – “His Twitter feed lacked insight,” she sniffs. When a friend later speaks about “infrequent hallucinations of transcendence,” Francine’s dogged pursuit of them springs to mind.

In appealingly titled subsequent chapters (“Francine, High School,” “Philip, Meanwhile”), Harmer leapfrogs back in time. Incendiary segments peer at Francine “living out a cliché about marriage and the death of desire” and her family’s “years of epic fighting,” even though ground zero is a well-appointed Ontario household.

As portrayed by Harmer, the key family members – twins Francine and Philip, and Victoria, their mother – are headstrong, cutting, and adamant scrappers, albeit well-spoken ones. Their scenes together are terrible wonders, arch but caustic in the way of a midnight-hued drawing-room comedy. Philip is earnest and conciliatory, in his view, while his sister forever acts with selfish caprice. Their mother, meanwhile, stores up barbed retorts with an intent to “eviscerate” both children.

Assigned cutesy nicknames (though they felt “treated like freaks, like mystics”) the twins grow apart over divergent passions – a rift that widens with the appearance of a “seemingly exemplary man” named Pastor Howie.  Newly – and zealously – devoted to virtuousness, Philip adulates the pastor. When Francine, already prone to “anarchic cynicism,” joins Howie’s youth group, the twins battle over the man, who does not resist the sexual interest of a teenage girl.

Decades after their teenage rivalry, Francine recollects, “Five years ago, they had both used every word that came into their minds to wound each other, like frantic archers reaching for a cache of arrows. They had both said hateful things.” Barring a miracle, the siblings will remain a “strange loop, trapped in an Escher drawing where you think the stairs will take you up, but you end up down.”

The novel ultimately loops to another reunion at the country home. Despite everyone’s good intentions the past gets dredged up. Further ruin ensues.

For Harmer, author of The Amateurs, this second novel evolves into a chance to reflect darkly on familial bonds. And to study the human animal, here so capable and incapable all at once.