Life hurts. Facile films use this truth to extract drama. The worst of them exploit the characters, and in turn, the audience, for effect. One comes out of the theater feeling used and with a bitter taste in your mouth.

Writer/Director Andrew Haigh’s coming of age drama, Lean on Pete, is not one of those films.

Though flawed at times by pacing and supporting character issues, it is held together, even elevated, by a inspired and understated performance by Charlie Plummer. The success and the humanity of the film rests on his thin shoulders and he carries it like a young DiCaprio.

The film’s structural and character strengths are built on contrasts. Charley Thompson (Plummer) is a 16 year old kid, new to a working class neighborhood of Portland, having to make a new start because of his father’s unsteady employment record, immaturity, and risky lifestyle choices.

The first thing we see is Charley unpacking his few things, placing his football trophies on the windowsill. A wide receiver, he has a rangy and wiry build, suited more for long distance running, which is his other activity, than for the pounding violence of the gridiron. He says he’s waiting until he stops growing to muscle up. And there you have a powerful metaphor for this film: Charley is a vulnerable kid, waiting to be grown up, waiting to toughen up. Life and the filmmakers, however, have more immediate plans. There will be no waiting. Charley’s strength building will not happen in a gym but on the road.

And like all good road movies and novels, The Adventures of Huckleberry Finn being a major model of this film, Charley needs a partner. That partner is Lean on Pete, a quarter horse on his last legs. Charley lives down the road from a third or fourth tier racetrack. This is not Churchill Downs. These are not thoroughbreds. Leave behind the glamour of Derby Day, the dapper trainers in suits, all the hats, even the long lap around the track, with all the jockey’s calibrations of speed and tactics. Quarter horses sprint. They run as fast as they can, and if they don’t run fast enough, unscrupulous trainers and jockeys will find ways to goad them on.

But to Charley, this is a glamours and intriguing world. He begins working for a trainer, Del (Steve Busemi putting in another nuanced and rock solid performance) and falls for his second string horse, Lean On Pete. Charley doesn’t know anything about horses or racing, but Del, despite his hard-boiled exterior, takes to the kid and appreciates his work ethic. He hires him as a stable boy, but warns him, as does Del’s jockey, Bonnie (Chloe Sevigny), “Don’t fall in love with the horses.” One can imagine Del and Bonnie, in their younger and sunnier days, falling in love with a horse or two, but those salad days are long gone. These are two characters at the declining ends of their careers. Beaten up and wounded by life, but still in game, though much compromised and wearing thin.

Is that Charley’s fate, too? Is it the responsibility of the adults in a child’s life to toughen them up, shatter their infantile illusions and prepare them for the pain, some of it to arise from bad luck but most of it self-inflicted?

Does a 16 year old see his life on such terms or is hope in the open road before him? A third of way into the film, Charley makes up his mind and takes to the road with Pete.

It’s in this section, that the sweetness of his character, the tenderness and vulnerability of Charley, is most clearly revealed. And it contains the best moments in the movie, and the best moments for Plummer. His monologues with Pete, as they move across the eastern Oregon and Wyoming plains anchor and sustain the film, give the film a reason for being.

But there are adventures ahead, new strangers, threatening and deadly situations, learning experiences, toughening up.

It’s in this parade of encounters that the film’s focus weakens. In committing to be life-like, the film must choose between developing supporting characters or letting them be tools in Charley’s progression. Sometimes they pay off, Charley’s aunt for instance, and sometimes, like with the two partying vets, the berated girl, and Steve Zahn’s street person, they are more symbols that souls, dark possible paths that Charley may find himself traveling if he’s not careful and lucky.

For like horse racing, to the bystander and gambler, it seems to be about luck and fortune; while for the trainer, the jockey, and the horse, it’s about hard work, grit, and, if fortunate, grace. Lean on Pete has plenty of all those, mostly in Charlie Plummer and the character he brings to aching and hopeful life.