The eponymous character is an aging thoroughbred whose days of winning on the racetrack are becoming fewer and farther between, but it is his friend and companion—a 15-year-old latchkey kid named Charley (Charlie Plummer)—who guides "Lean on Pete" through a narrative of stark, bristling beauty. At first glance, the film—based on the 2010 novel by Willy Vlautin—appears to be a boy-and-his-horse story, a bittersweet saga fit for the whole family. In reality, it is an altogether darker drama, one which sends this pair on an eye-opening, sometimes harrowing odyssey across the American West. Writer-director Andrew Haigh (2011's "Weekend") has made a tough, touching, marvelously observant picture, one which consistently reinvents itself over a two-hour running time of hardscrabble humanity and yearning solace.

Charlie Plummer is an emotionally raw revelation as Charley, a teenager who has recently moved to Portland, Oregon, with his blue-collar, seldomly reliable father Ray (Travis Fimmel). Forced to become independent and often without enough food in the house, he takes a summer job helping out horse trainer Del (Steve Buscemi). Charley is at first wide-eyed over and intrigued by the horse-racing circuit, befriending longtime jockey Bonnie (Chloë Sevigny) and taking a particular liking to Lean on Pete. When a series of untimely circumstances occur and it appears Pete's life may be in danger, a desperate, grieving Charley hits the open road with his new friend. His goal is to ultimately track down his Aunt Margey (Alison Elliott), an estranged relative who showed him kindness and love as a kid, but the path to this uncertain destination is paved with more hairpin turns and unexpected hardships than he can possibly anticipate.

Everyone in "Lean on Pete" is written with an enduring specificity. They have lives, and pasts, and stories to tell, even if most are simply passing through. This attention to detail ensures even the smallest of roles—a teenage girl (Ayanna Berkshire) mistreated by her belligerent grandfather (Bob Olin); a slippery unemployed alcoholic (Steve Zahn) and his much younger girlfriend (Rachel Perrell Fosket); Ray's latest married fling (Amy Seimetz), who stays long enough to fix Charley breakfast—casts an enduring imprint on Charley's journey. The more prominent supporting players are equally authentic, from Steve Buscemi's (2015's "The Cobbler") hot-and-cold Del, taking Charley under his wing and refusing to pull punches over the cutthroat world of horse racing, to Chloë Sevigny's (2017's "The Snowman") Bonnie, a jockey vet weary but accepting of the profession in which she's found herself, to Travis Fimmel's (2016's "Maggie's Plan") Ray, Charley's immature but not altogether uncaring father. Tough to take but impossible to turn away from, "Lean on Pete" is unforgiving until, at long last, it isn't, an indelible, remarkably moving glimpse into the margins of American life as seen from the point of view of a boy in search of a safe place to call home.