A man wakes up in a field hospital, not knowing who or where he is. He takes in everything: bandaged patients, a nurse, an astounded doctor who tests his reflexes and memory. As he recovers, his past comes back to him. He recalls his name and what’s happened. Most importantly, he learns his sister and her family have been murdered.

Paulette Jiles’ latest novel, “Chenneville,” is a gritty, atmospheric revenge story, set in a nation shattered by the Civil War. The narrator is John Chenneville, 32, 6-foot-3, heir to a tobacco estate outside St. Louis. While fighting for the Union Army, John suffers a brain injury in a barge explosion. Formerly a fancy-pants kid, coddled by servants, he becomes, in Jiles’ skilled hands, a shrewd and fearless bear of a man, seeking justice.

After months of recovery, John is allowed to return home, where he finds the family estate in shambles and his mother traumatized. When his uncle breaks the news about his sister’s murder, John’s confusion turns to rage and he focuses on revenge. He practices walking the crossbeam in the barn to regain balance, shoots at bottles until his aim is steady, trains himself to turn slowly in the saddle so as not to get dizzy. Eventually, he sets out into a broken, lawless land.

For readers hesitant to invest 300 pages on a man bent on settling a score, rest assured John is more than a clichéd cowboy and Jiles’ descriptions are less boot-crushing-cigarette-butt macho prose and more sunlight-piercing-the-understory imagery.

As John pursues his quarry — shaking down miscreants, evading a U.S. marshal, falling for a female telegrapher — a strange thing happens: We root for him.

But we cheer him not so much because he’s been wronged (the murderer is entirely depraved), but because he’s a complex human who, in order not to fall off his horse, must literally focus on the natural world. It’s good to ride in the saddle of a man who sees “Bobolinks rode the telegraph wires and greeted the May mornings with a cascade of wild notes.”