Starring Matthias Schoenaerts. Rated PG

“I’m not good with people.” That’s one of the first things to emerge from Roman Coleman, a taciturn prison inmate played by Belgian actor Matthias Schoenaerts, who previously brooded through international efforts like Rust and Bone and Far From the Madding Crowd. You get the feeling that Roman’s fellow inmates would feel no more surprised to hear him read poetry in flawless French or Flemish than to hear him say a simple yes or no.

Only near The Mustang’s end is there a hint of what landed him in a max-security joint in the Nevada desert. Some kind of violence brought him there, just as his passivity in the face of authority (in the form of a psychologist played by Connie Britton) gets him into a program that pairs inmates with wild horses that need to be broken, trained, and auctioned for profit. Roman gets hooked on horses, so it’s surprising that when he finally lashes out, he goes all Blazing Saddles on his charge, a black-maned stallion everyone else refuses to ride. Fortunately, he’s forgiven by the program’s irascible chief (82-year-old Bruce Dern), who sees something in the bull-like inmate.

Subtlety of message is not the strength of this debut feature for French actor turned director Laure de Clermont-Tonnerre. She wrote it with the symmetrically named Brock Norman Brock, and their script is not as interesting as its delivery. The leisurely tone here is reminiscent of both The Rider and Lean on Pete, recent efforts about lost youngsters who seek redemption through nobly rebellious steeds. The Mustang’s intensity comes from the setting, the ongoing tug of war between Roman and his inner beast, and battles with his grown daughter (Gideon Adlon), whose visits break the monotony.

Extraneous subplots involving drug-­running and inmate attacks threaten to make the movie less special. It’s inescapably ironic that when we get to that auction, Roman and the other riders sing soulfully about “The land of the free” under the watchful eyes of men with high-powered weapons.