“Small trees had attacked my parents’ house at the foundation,” says Joe Coutts, the 13-year-old narrator, in the opening sentence of The Round House (Harper), Louise Erdrich’s latest novel. They were just seedlings, but they’d grown into the cement blocks, and Joe says it’s “difficult to pry them loose.”

He does his best with a rusted dandelion fork. Alongside him, his father wields a fireplace poker, “probably doing more harm than good. … He was surely making convenient holes in the mortar for next year’s seedlings.”

The father gives up, the afternoon passes, the North Dakota reservation on which the family lives grows quiet­—but Joe labors on. “It seemed increasingly important to me that each one of these invaders be removed down to the very tip of the root, where all the vital growth was concentrated.”

While Joe exhumes the invaders as best he can, his mother is being raped. The Round House is about that attack, and the damage it inflicts not only on his mother but on the whole family, and, ultimately, on Joe’s friends as well.

Violence against Native American women is rampant. In an afterword, Erdrich points to shocking statistics cited by a 2009 Amnesty International report: one in three Native women is raped—they’re more than twice as likely to be raped or sexually assaulted as other women in the U.S. Erdrich writes, too, that 86 percent of rapes and sexual assaults are perpetrated by non-Native men, though that figure, based on a Justice Department survey taken more than a decade ago, is questionable. The Amnesty report notes recent studies putting the figure at 58 percent, but that’s dubious as well: sexual assault is vastly underreported, which makes data on the profiles of perpetrators less reliable.

The offenders are rarely prosecuted; as Erdrich writes, a “tangle of laws” makes it harder to prosecute rape cases on reservations.

There’s also a tangle of causes of the extensive violence against Native American women. “Rape, according to Indian women, has been distressingly common for generations,” a New York Times story observed last year. The reasons are poorly understood, the Times said, “but explanations include a breakdown in the family structure, a lack of discussion about sexual violence and alcohol abuse.”

Louise ErdrichCredit: Paul Emmel

It’s always been easier to focus on stranger violence than violence within the family, and the harm done by outsiders is the cause The Round House takes up. Joe’s mother, Geraldine, is raped by a white man who hates Indians. The assault is particularly grotesque: a young Indian woman is attacked at the same time, and the woman’s baby is on hand. The perpetrator douses Geraldine and the other woman with gasoline, intent on burning up the “evidence,” as he calls them. “I am really one sick fuck,” he says.

The Coutts family is beyond reproach—Joe’s father is a tribal judge, Geraldine a tribal enrollment specialist. They’re kind people and loving parents. The perpetrator is beyond redemption—loathsome, self-pitying, manipulative. His parents were wicked too. They owned a gas station-grocery on fee land surrounded by tribal trust land, and gouged their Indian clientele.

The perp’s mother was a “frail-looking little old white lady” but her “sense of entitlement was compelling,” Joe’s father tells him. She was “venomous,” and maybe her son had “absorbed her poison.” The perp’s sister isn’t toxic like the rest of the family—but that’s because she was rescued from her parents and raised by Indians. She tells Joe the attack occurred because her brother “set loose his monster. Not everybody’s got a monster, and most who do keep it locked up.”

Because Geraldine is assaulted near a junction of tribal, state park, and “fee” land—land sold by the tribe—it’s not clear who has jurisdiction, and Joe ultimately feels obliged to prosecute the crime in his own way. After he does, his thoughts return to those seedlings he dug out from underneath his parents’ house: “How tough those roots had clung. Maybe they had pulled out the blocks that held our house up. And how funny, strange, that a thing can grow so powerful even when planted in the wrong place.”

Readers are fond of tales about important social issues where good and evil are clear. The Round House was a best seller and won last year’s National Book Award.

But the roots that upend a family often don’t wander in from the wrong place. They can be an even greater challenge when they’re homegrown. We learn more from a story about the internal foe than we do from one about the outsider who unleashes his monster on the innocent.