Outta the way, Mr Chips. And if you see Miss Jean Brodie, tell her to go take a flying leap. When a film director makes a movie about school these days, tweeds are out. It’s all flak jackets, switchblades and sub-machineguns stuffed down your Calvin Kleins.

School is macho-land, no place for ladies unless they’re 17-year-old Chicana nymphets who live in rusty caravans or very gorgeous, blonde and blue eyed teachers just waiting for someone to lurve. At least, that’s what it’s like in Hollywood’s newest academic action picture. It’s called 187 which, in case you’re not up on your American law enforcement talk is police code for homicide. But this, as you’ll find out soon enough, isn’t just any old homicide.

In Kevin (Braveheart and Waterworld) Reynolds’ film, homicide is almost comic relief. In the classrooms, corridors and playgrounds - not to mention the staffrooms - fear, hatred and despair drip off the grimy walls. Samuel L Jackson (best known as the philosophising hitman in Pulp Fiction) plays Trevor Garfield, a black, middle-aged science teacher who gives every ounce of his creativity and dedication to the lazy, lippy, licentious kids he teaches at a run-down Brooklyn high school. Unfortunately, another thing he gives to the meanest and most psychopathic of them is an F in science, which is not taken very kindly. And just to show his displeasure, the failed gangster creates a colander motif in Mr G’s back with a big, ugly nail.

One year later, Trevor’s getting ready for his first day back at school since his stabbing, this time as a substitute (supply) teacher. Like many members of his profession, he says a prayer and wipes away a tear before leaving home. This time, he’s on the other side of the continent. Where he rode his bike through the filthy grey rain of New York City before, now he drives his car through the filthy brown smog of Los Angeles.

His new school, all neo-Spanish design on the outside, is something else within. A peevish teacher stands outside metal detecting the students as they enter. At least there are no more big nails to worry about. But within minutes, Trevor discovers a gun in the desk of another teacher. On this, his first day back, he’s called a muthafucka, comes upon students fornicating in the playground and sits in a staffroom that is literally under siege at lunchtime. This place makes his school back in Brooklyn look like Eton.

But Mr G is a forbearing kind of guy and quickly earns the admiration of teacher Ellen and tarty but clever student Rita. He may be having to take hits on his inhaler every five minutes and pray a lot, but he comes across as cool, committed and in control. And he keeps up the veneer even when a couple of particularly nasty irritants in his life, student gangsters who threaten Ellen and him, are mysteriously found dead and all the other kids accuse him of the murders.

I won’t give the entire plot away, but suffice it to say that the movie becomes an odd fusion of To Sir With Love meets Death Wish. And the ending isn’t very nice (unless you’re a forensic pathologist), although the epilogue gives as strong an affirmation of the teaching profession as you’re likely to get outside a National Union of Teachers gathering.

The screenplay was written by Scott Yagemann, who himself taught as a substitute teacher in the L A school system for seven years. Like Trevor, Yagemann was threatened with murder by a student. And like his hero, he found himself having homicidal thoughts when faced by a particularly nasty student - and says he knows that he isn’t the only teacher who has twisted fantasies like that.

For his part, director Reynolds visited a number of schools to get a feel of what sort of places they were. What he found was “a system that grinds up people. Teachers like Trevor start off being really selfless. But to survive, they find they have to resort to taking the path of least resistance and come to feel terrible about themselves. In my opinion, the most damaging thing is the day-to-day anxiety and the mental intimidation. They take their toll. I was shocked by the disillusionment of the teachers I met.”

And what of the violence, which for British audiences will have more echoes of A Clockwork Orange than their local comprehensive? “Of course, this is a worst case scenario. But violence in schools is happening a lot more often than people realise.” The film has had a mixed reaction from teachers. “Some teachers have said ‘thank you.’ At the end of the screening at the Edinburgh Film Festival, a teacher came up and told me how he’d been nearly beaten to death by students a couple of years ago,” says Reynolds.

But others have expressed outrage. “I’ve been upset by what some people have been saying. This film doesn’t say that violence is the answer. I don’t have a solution . . . but does that mean I can’t point out the problem?” TES arts, page 9 187 opens in selected cinemas around the country today