In Andrew Haigh’s moving indie drama Lean on Pete, a motherless 15-year-old boy in Portland, Oregon, gets a part-time job caring for horses at the local racetrack and bonds with a five-year-old quarter horse named Pete; when the stallion begins losing and faces a trip to the glue factory, young Charley (Charlie Plummer) makes off with Pete and the two set out on a treacherous cross-country journey together. A quietly observant filmmaker, Haigh understands the need for connection: his breakthrough feature, Weekend (2011), traced a gay romance through its heady first days, and his acclaimed 45 Years (2015) gave Charlotte Rampling one of her best roles as a wife suddenly alienated from her longtime husband. Lean on Pete, adapted from a novel by Willy Vlautin, turns on the extraordinary connection between Pete and the silent Charley—who, in his emotional outlook, often seems more equine than human.

Trust figures heavily in Lean on Pete, because Charley and Pete are both so defenseless against the world. Every horseman knows that, to win a horse’s cooperation, you need to convince it that you’re looking out for its safety, and Charley understands this thoroughly: from the moment he meets Pete, he’s all about the horse. The longer he works at the racetrack, though, the more he begins to understand that the horses’ well-being is secondary. “Every horse is just a piece of shit,” declares Del, who’s spent decades in the business and once owned 20 horses. Charley strikes up a friendship with Bonnie (Chloë Sevigny), the jockey who rides Pete, but she too turns out to be untrustworthy; after Pete wins a race, Bonnie confesses to Charley that she was using a device hidden under the saddle to give Pete an electrical shock.

Directed by Andrew Haigh. R, 121 min.