Even in a country that once attempted to ban alcohol, a stiff drink after a hard day is a widely accepted refuge. It’s rare, however, to find a movie that’s empathetic toward those who go further than that: people like Half Nelson’s Dan, who relieves career stress by smoking crack, or Factotum’s Henry, who decides to skip the job and go straight to the drink. The protagonists of these films, villains by the standards of most American movies, are treated not as heroes but as something more interesting: fully drawn individuals characterized not only by pivotal mistakes but also by their reasons for making them.

Leaving no doubt that it’s a workplace parable, Half Nelson opens with a shot of its central character’s face, accompanied by the sound of an alarm clock. Dan Dunne (Ryan Gosling) teaches 8th-grade history and coaches girls’ basketball at a school only natives could identify as being in Brooklyn. He’s impassioned about his subject, which he imparts in Hegelian terms, and committed to such figures as Gandhi, Cesar Chavez, and Martin Luther King Jr. Yet somehow Dan can’t get his class in sync with the official Civil Rights Movement syllabus he’s supposed to be teaching or engage his African-American and Latino students. The only one he seems to be reaching is 13-year-old Drey (Shareeka Epps), who also plays on the team Dan coaches.

One day after practice, Dan curls up in a toilet stall in the empty girls’ locker room and lights a crack pipe. Drey finds him there, a moment that alters their relationship without any substantial words being spoken. Drey’s brother is in jail, keeping his mouth shut to benefit local dealer Frank (the always compelling Anthony Mackie). Frank is cultivating Drey, hoping to enlist her as a drug courier. Dan intends to prevent this, but he lacks a certain moral authority. He is, after all, one of Frank’s customers.

Director Ryan Fleck, who co-scripted Half Nelson with its editor (and his girlfriend) Anna Boden, knows how this sort of fable is supposed to proceed. The earnest white man redeems the at-risk black student and maybe even—like Sean Connery trying out “dawg” in Finding Forrester—picks up some new slang in the bargain. Fortunately for the viewer, Dan is nobody’s idea of a redeemer. He wants to do the right thing, but he just doesn’t have the strength—even when his will isn’t sapped by cocaine or booze. In one of the film’s pitch-perfect scenes, Dan goes to confront Frank, and a battle seems imminent. But then Dan loses his concentration, and Frank offers him a drink. That’s not how things are supposed to work in the movies, but it’s often how they go in life.

The lack of resolution can be a drawback. The movie’s ending is underwhelming, although it’s preferable to the sort of big finish that would have fatally disrupted the fundamental tone. And Fleck indulges himself with the soundtrack, which includes overstated incidental music by Broken Social Scene as well as a few songs that are jarringly out of place. It seems unlikely that Billy Bragg’s “A New England” would be playing at the bar where Dan goes “looking for another girl” he will attempt to charm by denouncing Bush’s lies about Iraq.

Elsewhere, however, the juxtapositions work well. A student’s report on the Attica prison uprising, for example, is followed by Drey’s visit to her brother in jail. These are the sort of links Dan wants his kids to make, even if he’s not sure they make any difference. The child of radical parents who now make embarrassing jokes about “Ebonics,” Dan wants to not only live up to their tattered ideals but also go beyond them into quandaries—such as black–white relations—that decidedly were not settled in the ’60s and ’70s. Sometimes, though, he just needs to slip out the back door and find a place where he can get stoned without anyone asking why.

Instead, Dan encounters Drey, who has lots of questions he should be prepared to answer. The relationship between the half-defeated teacher and his precariously situated student is the film’s crux, requiring subtle work from Gosling (who was stunning as the secretly Jewish neo-Nazi in The Believer) and Epps (who’s making her debut). The performances are utterly natural, seemingly as offhand as Andrij Parekh’s hand-held cinematography. Both are loose and unforced, yet tightly focused when that’s required. Gosling’s Dan is an ideologue who’s not sure he can be fully human; Epps’ Drey is the child who forces him to be. It’s a relationship that moves beyond theory, which is exactly where Dan needs to go.