For most of this story, the young filly that Will Testerman plans to train up and sell for a big payoff is nameless. Will calls her simply “the filly” or sometimes “Tick,” after her dam, Sally’s Quick Ticket. Very late in the novel, at a barn in California where Will has come to learn what he can about training horses for polo, a disfigured Argentine boy suggests a name for the horse: Boleto, the Spanish word for ticket. It’s an easy metaphor — the filly is Will’s ticket out of Wyoming, his ticket into the monied world of polo. But then the boy goes on to tell, in a few brief lines, the terrible story of his disfigurement, an injury, he says offhandedly, that was his ticket to America.

Boleto,” Alyson Hagy’s third novel, is embroidered with such stories, stories that throw light not only on the world Will knows, but also a larger, darker, more perilous world that, at 23, he only dimly apprehends.

The novel’s slender plot follows him through three seasons of a single year: spring in Lost Cabin, Wyo., at the Testermans’ small ranch; summer at an old-style guest ranch in the mountains east of Yellowstone; and autumn at a swanky polo estancia in California. It’s a slight framework, but as Hagy slips into its many side channels — stories that branch off from the main stem, then rejoin it — the novel begins slowly and quietly to gather power and movement.

In Wyoming, Will buys the filly and starts his patient work with her, intending this time to take no wrong steps. But his life here is shadowed by events of the past: a relationship that soured, a job on the show-horse circuit that went badly wrong, the mysterious disappearance of a Lost Cabin woman that for a while had cast suspicion on Will. His father, trapped by money worries, is a man he cannot seem to please. His mother, a schoolteacher whose cancer is in remission, tells him stories about the wider world and asks him every day on the drive to school, “Who are you today, Will Testerman?”

At the Black Bell Ranch, where he spends the summer months working as corral boss, events unfold with the unpredictable rhythm of mountain weather: a dalliance with a cabin girl, card games that turn ugly, trail rides that finish in lightning and pouring rain. Crucially, he must deal with a drunken wrangler who had once been his boss, a man on the way down whose past life in vaguely troubling fashion mirrors his own.

‘Boleto’ by Alyson Hagy (Graywolf Press)

In California, the stablehands are Argentine boys who have each been damaged by some unrevealed accident or injury. Will has come to the polo fields having already learned that “people with money, young people or old, occupied the world in ways he could hardly imagine,” but the men he meets in this high-stakes game are perhaps more dangerous than any he has known.

As Will goes about the slow, scrupulously observed work of schooling the filly, he tells her the history of his family and particularly of his great-grandmother’s hard life in North Dakota; and stories about horses he has known, the “important horses in his life that had not died or been sold off.” There are, as well, the stories he does not tell her, of horses that died in terrible circumstances — one by his own hand. “It was the way he’d heard you should do it if you wanted to be sure. You didn’t want to shoot them in the forehead, where the bone was thick. You wanted to do it in the eye. To be sure.”

In her gift for the language of horses, as in the beauty of her prose, Hagy will inevitably recall Annie Proulx, Kent ­Haruf and Cormac McCarthy. But she is writing as much about wealth and class, about work and privilege, as about horses and the Western landscape.

“I don’t plan on getting ripped off,” Will tells his brother. “I just want to sell a really nice horse.” Some readers might wonder, after 250 pages, if it was all for that. Only that. Which may, to others, be exactly the point.

Gloss is the author of several novels, including most recently “The Hearts of Horses.”

BOLETO

By Alyson Hagy

Graywolf.

251 pp. $24