Selena, the “Queen of Tejano Music,” appears in an enthralling scene in Marcela Fuentes’s debut novel, “Malas.” At a show just weeks before she was murdered, the singer performs “¿Qué Creías?,” a mariachi ballad in which a wronged woman tells off a man who thinks she’ll stay with him. For the novel’s teenage protagonist, Lulu Mun~oz, it’s a moment of perfect bliss and belonging that comes after her own defiance against the man looming over her life: her father, who forbids concerts and thinks teenage girls shouldn’t be “out running the streets.”

Set in La Cienega, Texas, a fictional town on the U.S.-Mexico border, “Malas” follows the intertwined lives of 14-year-old Lulu, who has a passion for punk despite her Selena fandom, and Pilar Aguirre, an elegant and mysterious recluse. Their stories begin decades apart — Pilar’s in 1951 and Lulu’s in 1994 — but meet in an unlikely friendship after Lulu’s grandmother’s funeral, where Pilar’s unwelcome appearance stirs Lulu’s curiosity.

Ever since Lulu’s mother died in an accident eight years earlier, her father has been spiraling into alcoholism and isolation, leaving Lulu to parent herself. A fiercely independent yet sensitive girl, Lulu finds refuge in her punk-norteño band and in her friendship with Pilar, until old family secrets come to light. Though her father had always attributed their family tragedies to an old curse, Lulu discovers that there is more to their misfortunes than magic or luck.

Lulu is a remarkably mature child who manages to get good grades despite ditching school often and sneaking out of her house late at night. Her father, a former Chicano activist, inserts himself into her life just enough to posture at parenthood or fuel family dramas. Fuentes’s older characters are flawed, often immature people struggling through traumas, addictions and all manner of bad decisions. It’s the young ones, especially girls and women, who are expected to bear the burden of generations’ worth of consequences.

The title of the book, “Malas,” is a play on the pervasive “bad woman” stereotype, which Lulu tells us is her father’s great fear. “If he’s not watching out, I might become a mala,” she says. “And for a Mexican man, a mala is the worst.” Pilar has long been stigmatized as a mala, with rumors — including infanticide — circulating outside her secluded hilltop home. Even her vanity marks her as a bad woman, recalling an iconic mala of Pilar’s generation, the Mexican actress María Félix. Pilar, too, has the haughtiness of a diva who refuses to fade in her twilight years, her high-arched eyebrows ever alert to the trespasses of men.

Fuentes’s borderlands make up a heterogenous landscape where cultural, ethnic and national identities converge and new ones are forged. “There are names for everybody and rules for the names,” Lulu says, and proceeds to rattle off a roster: naco, fresa, Chicano, Mexican, Mexican American, Hispanic. Add to these labels punk, metal head, stoner, Goth, New Wave, skater, marijuano and heavy-metal Satanist. Lulu loves them all.

They are part of a gently historicized portrait of the border, which Fuentes reminds us is a fluid space, but was as porous as river sand in the 1990s: “It was narrow, but men and women slipped back and forth across the border, shoes in hand, and hardly more than wet trouser cuffs to show for it.” Today, those attempting to cross it face a militarized instrument of death.

“Malas” is an antidote for the hard-line essentialism that has made this world an intolerant, violent place. Fuentes humanizes seemingly insoluble conflicts, both generational and cultural, with imperfect characters who are just doing their best, even when they know they are screwing up. She gives them something that many of us nonfictional people living and messing up in the world could use, and give back — grace.