Inspirational sports stories are hardly cinema rarities, but this documentary by Dan Lindsay and T.J. Martin is a good example of the genre, made better by the fact that it’s true rather than ramped-up fiction. It follows the fortunes of the Manassas Tigers, the football team of an inner-city West Memphis high school, during the 2009 season, during which they reversed their reputation as go-to losers and overcame myriad obstacles to become a serious challenger for a district—and maybe even state—title.

From the purely gridiron perspective “Undefeated” isn’t really an accurate title: the Tigers actually lose their opening games badly before turning things around. But though their on-field performance is a significant part of the picture’s story—the team hasn’t had a winning season in aeons, and have never won a playoff game in the school’s century-long history—the real emphasis is on three of the players and their remarkable coach.

The latter is Bill Courtney, a paunchy, gregarious fellow who makes a living running a lumberyard while volunteering to rebuild a team long considered a laughingstock in Tennessee football circles. Courtney is a driven but principled guy, as concerned about his players as he is about winning games and seeing the team’s success as a means of helping to revive the spirit of the school’s blighted neighborhood. Plainspoken and surprisingly introspective, he also frets about neglecting his own kids while devoting so much time to the team.

Among his players, Lindsay and Martin focus on three. One is O.C. Brown, who’s already being looked at by college scouts but has to improve his grades and pass the entrance exams if he’s going to move on to the next educational level. At one point the narrative takes a “Blind Side” turn when the easygoing kid is—with the approval of his supportive grandma—welcomed into the home of an assistant coach for special tutoring. O.C.’s reaction to an environment very different from the one he grew up in is amusingly understated, and his story has a really affecting close.

The other two “star” players are Chavis Daniels, a hot-tempered kid just back from a stint in juvie whose outbursts might get him dumped from the team—and from school, and Montriel “Money” Brown, a bright, amiable lineman whose ability to play is threatened by a serious injury.

There are illuminating moments throughout “Undefeated”—a dust-up between Chavis and “Money” and a later speech by the former about the latter at an impromptu award ceremony, a digression by “Money” about his pet turtle that shows his vulnerable side—and the ending is a surprising mixture of uplift and reality, demonstrating that one can be undefeated on an off the field. The documentary might not do for pigskin what “Hoop Dreams” did for basketball, but on its own terms it’s a compelling slice of inner-city life with an affectingly hopeful message.