HALF NELSON is a film named after a wrestling chokehold and stars Ryan Gosling as Dan Dunne, a young teacher on the ropes of life. Not for him an adversary in lycra, knee boots and a cape:

instead, Dan gets to wrestle with himself and his conscience. It's a fight he is losing day by day. He turns up for class with eyes bruised from lack of sleep; not only can he not get a hold on himself, but he cannot pin down a slippery drugs habit. He snuffles cocaine like a man gasping for air.

His nose begins to gush blood in front of his class of underprivileged 13-year-olds. In the first of two memorable scenes, he knocks himself out afterhours in the school gym smoking crack, to be found on the floor by his 13-year-old pupil Drey (Shareeka Epps). Chalk that one up for the next teacher-parent meeting.

But while Dan beats himself up, he is fiercely passionate about the lives of his students. The scene marks the start of a bond between himself and Drey, an unusual relationship founded on mutual support. He must hit the bottom before he can find his way to bounce back up again; she finds that the only moral guidance she can get in life is from a teacher who is a crack addict. This is one of the joys of Half Nelson, a film that inverts all the typical lessons of the classroom-film genre where until now, teacher's idea of homework was to hand out 100 lines of insufferable inspiration.

Drey has the kind of problems we have come to expect from a 13-year-old black child growing up in poorly Brooklyn . . . an overworked, never-at-home mother, an absentee father, and a drug dealer in the form of Frank (Anthony Mackie), a slyly amiable fellow whose narcotics trade resulted in Drey's brother going to jail. So he tries to look after Drey in his own way, and plans for her to gain work experience in the home deliveries section of his drugs operation. In another scene that hovers long in the mind, Drey, well past her bedtime, arrives at a motel room with a delivery of drugs. She discovers it is for her teacher Dan and the prostitutes he has employed to party with him into the night. As their eyes meet in mutual shame across the room, you cower under your seat with embarrassment just watching it.

But the episode propels Dan onto the ropes and back out fighting for his dignity and for the girl's better future.

Half Nelson is written by firsttimers Ryan Fleck and Anna Boden, and in his direction, Fleck adopts an easy, intimate docurealism. It's a film that alludes to many life lessons, but it never preaches. I would class it among a breed that could be called Americanis miserabilis . . . navelgazing US indie movies that deal with inner turmoil, crappy lives, irritating families, substance abuse and 365 shades of melancholy.

What are these films trying to tell us? Perhaps that America is an alienating and depressing place to live for many, made worse by seven years of George Bush. What Half Nelson does so well though, is to root this misery in something tangible . . . the American political landscape. Dan teaches the push and pull of US history to his young class through the model of dialectics. You can feel him urging them into an antithesis of rebellion.

"There are some changes you can't control, but there are others you can, " he says. And Fleck intercuts the film with scraps from civil rights marches and Vietnam demonstrations to remind us of a time when America heaved with revolutionary potential. But Dan struggles with feelings of ineffectualness and strangled politicism, a man who believes that in a time of the Patriotic Act, to be political, even revolutionary, is useless. "One man alone means nothing, " he tells his mother. This crafted study of one man's inadequacy is imbued with a deep pessimism about modern America.

Previously seen in The United States of Leland, Canadian actor Ryan Gosling is a revelation, a freewheeling performance of intelligence unhinged by selfdestruction which saw him rightly nominated for a best actor Oscar.

Almost as good is young actress Shareeka Epps, plucked from obscurity for the role. She is 13 going on 60 and already has the look of a woman who would give you a box around the lugs if you dared cross her.