Sebastian Barry, a gifted Irish writer whose early books were set in his home country, has recently turned his eye to these shores. The results have been reliably interesting — and sometimes very moving. "Days Without End," his 2017 novel about forbidden love during the Civil War, is a daring piece of fiction. A new sequel, set against a backdrop of brutality in the post-bellum South, is just as vivid.

"A Thousand Moons" focuses on Winona Cole, a member of the Lakota tribe. Orphaned when government troops murdered her family, she was adopted by John Cole and Thomas McNulty, ex-soldiers who themselves killed Native Americans. The law won't recognize their relationship, but the men are all but married. Together with Rosalee and Tennyson Bouguereau, siblings and former slaves, they work the land and share a home in Tennessee. A family forged under harrowing circumstances, they're about to be tested again.

It's the 1870s, and Winona, a teenage math whiz, is a bookkeeper in a law office filled with documents chronicling the deadly persecution of Native people. "It had proved impossible to civilize us, the documents said. It made me cry to read such things," she says.

One night, Winona is raped. The attacker's identity is unclear. She stays quiet, aware that telling the authorities might place her in further danger. The crime isn't an isolated event. Since the Civil War, many on the losing side have grown increasingly embittered. Violent white supremacists are running wild; an innocent black man is lynched. "Now truly we are citizens of the devil's country," says a distraught local.

Terror is visited upon Winona's household again when Tennyson, a talented amateur artist, is assaulted by racists. His drawings of animals soon take on dark overtones. Shaken by his pain, Winona arms herself and rides off in search of justice. It will be a revelatory trip.

Along with memorable characters and a powerful story line, "A Thousand Moons" blends bygone language with rich imagery. Winona favors pants she calls "trews" and uses verbs like "enrichen." She moves across a landscape dotted with torched houses as "black as the throats of chimneys." And like its predecessor, this novel considers timeless ideas like tolerance and human rights. Taken together, these books stand as a sustained interrogation of this country's founding ideas and myths.

In a moment of intense debate over who gets to tell what kind of stories, Barry's decision to write in the voice of a Native American woman won't please everyone. That's OK, these are important discussions to have. But this isn't an exploitative book. Barry's affection and respect for Winona is palpable. "A Thousand Moons" is a sincere and well-written novel starring an intrepid, self-sufficient heroine. We can never have too many of these.

Kevin Canfield is a New York City-based writer.