By Jake Coyle, AP Film Writer

There is painfully little love, except for the warm and compassionate filmmaking itself, in Andrew Haigh's tender and heartbreaking coming-of-age drama "Lean on Pete."

In his first American film, Haigh, the British director of "45 Years" and "Weekend," proves every bit as adept at burrowing into fragile human intimacies across a vast Western landscape as he showed in his earlier, more cloistered dramas.

He makes precisely tuned, quiet movies that speak volumes about their characters. Fittingly, it's the sound design that you notice first in "Lean on Pete." In the opening scenes, 15-year-old Charley Thompson (Charlie Plummer) goes for a jog in his low-income Portland, Oregon, neighborhood, and the sounds of passing traffic and nearby machinery grate coarsely against Charley's free and easy breathing. It will be a long time before he can find peace.

Charley lives with his single father (Travis Fimmel), a jovial blue-collar guy who bounces from job to job and girlfriend to girlfriend. Having recently arrived from Spokane, Charley's days, and some nights, are idle and lonely, with little to no food in the house.

Plummer, who played the kidnapped Getty grandson in Ridley Scott's "All the Money in the World," gives a natural and crushingly sweet breakthrough performance. His Charley is a meek, sheepish kid yearning for a little stability. When a woman his dad brings home buys groceries and makes eggs for breakfast, he hopefully asks his father if she might stick around.

On one of his runs, Charley notices a nearby racetrack and is instinctually drawn to it. He meets the grizzled, ethically shabby horse owner Del (Steve Buscemi, straying far from his natural environment, New York), who gives him a few bucks for an odd job. Charley asks if he needs any more help, "help with anything," he says, eager to just stick around the horses.

Charley immediately takes to Del's oldest, least flashy but sturdy horse: Lean on Pete, a five-year-old quarterhorse. Del and his favorite jockey, Bonnie (Chloe Sevigny), caution him about growing too attached. Pete won't last much longer; Del is trying to squeeze a few more races out of him before selling him off. This is a horse racing world far from Churchill Downs, of hardscrabble courses, set off by ropes, with rampant cheating — at least for Del. "He's not a pet," says Bonnie. "He's just a horse."

It's a warning that could double for "Lean on Pete." Haigh's film might appear a mushy, Disney-style tale of boy-meet-horse, but "Lean on Pete," based on the novel by Willy Vlautin, is about a crueler world without room for sentimentality. Just as Charley is settling into life at the track, a violent tragedy upsets his already tenuous existence.

Charley steals Pete and, looking for a long-lost aunt, sets out on a woeful odyssey through a seldom-seen America. Everyone Charley encounters is just scrapping by, many of them compromising themselves for the little security they can manage. Spanning Western plains and urban homeless shelters, the portrait of America in "Lean on Pete" grows increasingly harsh.

But it's less Haigh's mournful view of American society — one that, for sure, rarely finds American movie screens — that makes the heartfelt "Lean on Pete" stay with you. It's Plummer's wounded, achingly alone Charley, humbly striving across a darkening land, holding on desperately.

"Lean on Pete," an A24 release, is rated R by the Motion Picture Association of America for "language and brief violence." Running time: 121 minutes. Three stars out of four.

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