'The Fire Inside' review: Stronger, more thoughtful than your average sports movie

It would be easy to dismiss "The Fire Inside" as "Rocky" set in Flint, Michigan. It's about an underdog boxer, it loves a good training montage, and it shares other characteristics with the classic and its successors.

But to do that would downplay the seriousness and intelligence brought to the story by director Rachel Morrison and screenwriter Barry Jenkins.

The picture follows the rise of Claressa Shields (Ryan Destiny), the champion professional boxer and mixed martial arts fighter. Before she turned pro, Shields became the first U.S. fighter to win consecutive Gold Medals at the Olympics, taking them home in 2012 and 2016.

The movie begins with Claressa as a child, walking into a gym run by Jason Crutchfield (Brian Tyree Henry) and forcing her way into being taken seriously. As the years pass, she becomes his prize fighter, training and qualifying for the 2012 Olympics in London when she was still a teenager.

Crutchfield, who works as a cable technician and earns no money off his boxing work, makes considerable sacrifices to help Claressa pursue her calling, including taking her under his roof to live with his wife and kids after she has a falling out with her mother.

Morrison, an acclaimed cinematographer ("Black Panther") making her directorial debut, recognizes something important and occasionally misunderstood by those working within the sports movie genre. The sport in question matters much less than the story behind it.

Working from a screenplay by Jenkins (who is also in theaters now as the director of "Mufasa: The Lion King"), Morrison zeros in on the relationships at the center of the picture, and the ways in which each of them informs who Claressa becomes.

In Jason, Claressa finds more than a coach: he's a mentor, a father, an advocate, and a person who brings trust and stability into a world defined in part by a difficult home life. At the same time, coaching her offers him the promise of something more and greater, the sort of achievement that just maybe means you'll have made a real impact on the world.

The strength of this bond gets reinforced by the performers, who are so good at playing off each other and conveying these intense emotions. It's also what underpins a large portion of the movie's drama, as this relationship faces strain when Claressa returns from her 2012 Gold Medal win to find that the opportunities are more limited for her than they are for a lot of her Olympic teammates.

The second most important relationship in "The Fire Inside" is that between Claressa and her hometown, captured by Morrison's cameras with an eye for its beauty rather than its grit. It's a place of family and community and kindness, but also struggle and pain. Claressa's journey requires reckoning with it all, but remembering what Jason tells her about the history of Flint and the stone that shares its name.

"It's a tough stone, flint," he says, "but it's strong as hell."