Reid Miller and Mark Wahlberg in Joe Bell.

An important and heart-wrenching true story leads to a well-intentioned but middling film with Joe Bell, a “departure” for Mark Wahlberg that results in some of the more uneven work of his career.

The film is based on the real-life events that led a man named Joe Bell (Wahlberg) to pledge to walk across the country in the name of his bullied son, Jadin (Reid Miller). Jadin has been a victim of harassment and violent abuse at his high school because he’s gay. Joe, a conflicted man in his own right, is determined to do something about the harm being done to his boy.

We first see Joe walking on the highway with Jadin, and the son is giving the old man some good-natured guff. Joe is a cranky, irritated sort, with Wahlberg’s work sometimes reminding me of Andy Samberg’s whiny impression of the actor during his “Mark Wahlberg Talks to Animals” sketches on Saturday Night Live. Joe struggles with his own homophobic tendencies—which come to the surface even as he’s walking across the country with his son to fight homophobia and bullying.

The movie works best when Wahlberg dials it down a bit—giving Miller a chance to shine. Miller is good despite being saddled with a few scenes that you could swear you’ve seen a thousand times before. That lack of originality is surprising, considering the screenplay’s pedigree: It written by the team of Larry McMurtry (who passed away earlier this year) and Diana Ossana, the duo responsible for the Oscar-winning Brokeback Mountain script. The film is directed by Reinaldo Marcus Green (Monsters and Men), and he doesn’t have a steady hand, especially when it comes to Wahlberg.

There are times when Joe Bell hits the right emotional notes, but the film is done in by the confusing Wahlberg performance and some terrible narrative choices; one choice in particular is a gigantic head-scratcher that robs the movie of its effectiveness. The gimmicky plot move badly damages the film in its first half, wasting some better moments deep into Joe Bell’s running time.

Joe Bell is not a well-made movie, but it is admirable in what it is trying to do. It’s well-meaning; it does bring some awareness to an important issue; and it does have solid work from Miller. I’m glad this movie got made—even though I don’t like it.

Joe Bell is playing at theaters across the valley.