Most teachers are alert to the drugs problem in their schools. Dan Dunne (Ryan Gosling), the Brooklyn history teacher in Half Nelson, is different. He is the drugs problem. Not for Dan the everyday addictions that plague the average teacher, such as caffeine or corduroy jackets: his poison is strictly class A.
Dan busily goes about his own self-destructive business, managing to hide his habit from his class of impressionable adolescents, until one girl walks in on him in a toilet cubicle when he is - what's the medical term? - stoned out of his box. Luckily for Dan, it's Drey (Shareeka Epps) who has discovered his dirty little secret. As well as having an old head on her shoulders, thanks to being forced to fend for herself in the absence of her estranged father and hard-working mother, Drey is already under the wing of a local dealer, Frank (Anthony Mackie), and consequently isn't fazed by the sight of Dan off his face on crack. The straightforward manner in which she mops his brow as he lies on the floor suggests she's been here before. What blossoms from this encounter, though, is friendship. Dan starts giving Drey lifts home from school. Drey hangs out at his apartment. Eventually, Dan feels protective enough to confront Frank about the influence he has over the girl, sweetly oblivious to the fact that the example he's setting is scarcely much better.
You might say that Frank, who has been keeping Drey in pocket money since her elder brother took the fall for him, has the child on a youth training scheme. Despite the off-putting example of her brother, whom she visits in prison, Drey seems happy to begin her working life with the kind of courier job that you don't mention on your CV. The magic of Shareeka Epps's performance lies in her ability to make this behaviour plausible and matter-of-fact, but not easily explained. Epps evokes Drey's maturity so convincingly that you wonder why she goes along with Frank's cheerful coercion. And then she will do something - an almost imperceptible wince when Dan tells her to spend time with people her own age, or a glimmer of fragility when she's on a drug-running errand - that makes you remember, with a jolt, that she's still only 13.
The horrible irony is that this girl, in dire need of a father figure, suddenly finds herself with two, both of whom are bad news. Like their young co-star, Gosling and Mackie jumble up the contradictions in their characters until you can't sift the positives from the negatives - until, in other words, you can appreciate precisely Drey's predicament in having to choose between rock and hard place, frying pan and fire.
Half Nelson sidesteps so many of the traps inherent in its subject matter that it is easier to say what it doesn't do than what it does. This being a non-judgemental, low-budget, American independent film, there are no big signposted moments of crisis. Scenes that would inspire much weeping and gnashing of teeth in a mainstream production are presented here almost casually. The director, Ryan Fleck, and his co-writer, Anna Boden, don't force the narrative to any banal conclusion; it might be argued that they don't force it to any conclusion at all, unless Dan's inability in the final scene to tell the most rudimentary "knock, knock" joke is intended to demonstrate the depths to which he's sunk.
What this sober film can't quite bring itself to admit is that Dan is a dynamic fellow. Never mind the drug habit, the antisocial tendencies, the nosebleeds: he's played by Ryan Gosling, for goodness' sake. The only way around this would have been to cast an uncharismatic actor in the lead role - wasn't Charlie Sheen or Ben Affleck available? As it is, ordinary Joes in the audience are likely to take a gander at Gosling, even at his most strung-out, and be moved to paraphrase When Harry Met Sally: "I'll have what he's having."
Pick of the week
Distant Voices, Still Lives (15)
dir: Terence Davies
British cinema at its most poetic in this 1988 memoir of a Liverpudlian childhood.
The Lives of Others (15)
dir: Florian Henckel von Donnersmarck
Oscar-winning thriller about dissidents in East Berlin.
Lights in the Dusk (PG)
dir: Aki Kaurismäki
Final part of Kaurismäki's "loser trilogy". An understated gem.