Anyone lucky enough to have seen the horseback riders of North Philadelphia in person knows firsthand the frisson that first glimpse produces: Is that really a horse? In the heart of Rust Belt Philly? At its best, the uneven but good-hearted family film "Concrete Cowboy" is animated by that same shock of disbelief and delight — made all the more appealing by the fact that it's Idris Elba coolly clip-clopping down the city's unforgiving streets.

Elba plays Harp, an ex-con who is part of an equestrian club based on the real-life Fletcher Street Urban Riding Club, where for the past century Black horseback riders have been stewards of one of Philadelphia's most storied traditions. Harp likes horses more than people — he even has one for a literal roommate — so when his 15-year-old son Cole (Caleb McLaughlin) shows up for some father-son time over the course of a summer, Harp is less than amused. Expelled from school and having plucked his mother's last nerve, Cole doesn't just need bonding — he needs an intervention before he takes a self-destructive, maybe even fatal, path.

Those are pretty familiar stakes, and "Concrete Cowboy" doesn't stray too much from what viewers will recognize as a tried-and-true formula. Based on Greg Neri's young-adult novel "Ghetto Cowboy," this coming-of-age tale features enough predictable conflicts, setbacks, tenderness and triumph to verge on the cliche.

But, in the hands of first-time director Ricky Staub, "Concrete Cowboy" also possesses gratifying moments of lyricism and authenticity, especially when the filmmaker immerses viewers in the life of the Fletcher Street stables, some of whose denizens show up here as supporting players. While Cole tries to get to know his strangely withholding father, he reconnects with his cousin Smush (Jharrel Jerome), who tries to entice Cole into a life of petty (and not-so-petty) crime.

The angels on his shoulder turn out to be Harp's neighbor Nessie, played by Lorraine Toussaint with a convincing combination of warmth, toughness and humor; while Cole learns to muck out stalls and handle skittish 1,000-pound animals, he's coached by a colorful gang of old hands, including a spirited ad hoc life coach named Paris (Jamil "Mil" Prattis), who schools the impulsive teenager in the ways of patience and self-discipline.

It's when the ensemble gathers — around trash-can campfires or on rides through the streets — that "Concrete Cowboy" comes most alive. Elba, who is a co-producer, makes the most of a character whose hostility would be off-putting without his inherent likability. As the movie reaches its melodramatic climax, the audience will see nearly every moment coming. But, even within the confines of its generic plot and sometimes stilted dialogue, "Concrete Cowboy" winds up being an engaging and moving family drama. Its sincerity, accomplished cast and proud Philadelphia roots manage to keep it real.

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Three stars. Rated R. Available on Netflix. Contains strong language throughout, drug use and some violence. 151 minutes.