Film: THE IRON GIANT: Hey kids, get a little iron in your soul

Now here's a thing: kids like to watch other kids being compassionate. Call it armchair emotion, call it rank hypocrisy, but the sort of children who push classmates' heads down the toilet and then flush the chain are still likely to go "ah!" when they see Elliot cherishing ET, or Pete petting his dragon.

Warner Brothers' The Iron Giant certainly aims to press similar buttons. It tells the story of Hogarth, a sensitive, fatherless American boy whose instinct to attack a huge, rampaging metal object does a 180-degree turn when he realises that the creature is in pain. The titular giant, trapped in a mess of spaghetti-hoop-like pylons, actually looks as if he's being crucified, making Hogarth's act of goodwill (he switches off the current) appear extra pious. And the pair's subsequent friendship, which includes Hogarth teaching the giant - all moon-white eyes and endearingly rigid mouth - how to talk, is a hymn to soft, nuzzly feelings.

So you may be surprised to learn that this cartoon is based on Ted Hughes's The Iron Man. The poet's 1968 story does have a little boy called Hogarth, and a mysterious Iron Man, but the kid doesn't teach the Iron Man anything and their relationship soon peters out. Hughes not only denies youngsters the urge to play parent, but the usual identification point. No such challenge here. Also missing is the tongue-prickling poetry - those vivid descriptions of the Iron Man's dinners ("the Iron Man chewed thoughtfully at this favourite titbit, a juicy, spicy old gas-stove") that make you want to try licking a chunk of metal yourself. The Iron Giant enjoys his food, but he's no gourmand.

What the film does have is something special all of its own - a take on Fifties America that is quite dazzlingly sophisticated. The film's director and writer, Brad Bird (who cut his teeth on The Simpsons and King of the Hill), has chosen to down-date Hughes's story, setting it in 1957 Maine, and in an aptly named town called Rockwell (after Norman) where the prevailing concerns of the community are Reds overtaking them in the space race and/or creeping under any beds. Their views are represented by Kent Mansley, a hawkish government agent. As he informs Hogarth darkly: "There's a foreign satellite orbiting the earth and all that that implies."

Someone else in Rockwell is obsessed with outsiders, but in this case because he thinks he is one. Dean (as in Moriarty) is a hip cat; he has posters of Kerouac on his wall, a yin-yang globe on his bathrobe and a habit of saying things like: "we kooks have got to stay together!" Cartoons don't normally dabble in "trendy" characters, so Dean - neurotic, witty and Elvis Presley-handsome - is something of a revelation. Cartoonist Robert Crumb admitted he had a crush on Bugs Bunny, but this is the first animated figure I've ever fancied. By day, Dean (voiced by Harry Connick Jr) runs a scrap-iron yard, which is how Hogarth and the Iron Giant come to befriend him. At night he turns the scrap into sculptures. "It's funny," he muses, more to himself than Hogarth, "people will pay money for scrap iron, but once I turn it into art I can't give it away."

That Kent and Dean are Hogarth's two polar-opposite "father" figures is clear. Hogarth, however, proves more complex. One-part Bart Simpson (he shares Bart's love of MAD comics), two-parts Lisa, Hogarth is a latch- key kid, forced to bring himself up while his mother (Jennifer Aniston) works in the local diner. He is thus able to live on a diet of tooth-rotting Twinkies, B-movies and comics, and this is where Bird's influence - his mini-thesis on trash culture and the imagination - makes itself felt.

We assume that with the arrival of the Iron Giant these sort of junk- culture pleasures will quickly make way for more organic, innocent ones. But no. Hogarth's dreams and chatter are endlessly informed by comics or TV. When he and Iron Giant are flying through the sky, he encourages the giant to put his arm out - "try doing it like Superman". And it's catching - the Iron Giant himself decides that he wants to be Superman.

That's how kids work. In the same way, Hogarth's vocabulary changes almost as soon as he meets Dean. "Don't wig out," he tells the giant, adopting the lingo of his beatnik pal. Even his big, tear-jerking final message to the metal man - "you are what you choose to be" - is an arty-farty line he's picked up from Dean. One accusation constantly levelled against millennium culture is that it has no new ideas. Bird makes a virtue of this, pointing up the basic human need to copy.

This puts Dean in a whole new light. He is desperate to be seen as different. Through his "art" he wants to transcend trash (literally and metaphorically). At one point, the Iron Giant accidentally chews a piece of Dean's work, then delicately (and most apologetically) tries to bend it back to its original state. As it happens, this attempt to "go backwards" creates a new, far more interesting shape. "It's good!" exclaims an astonished Dean, having finally got it.

The film itself is testament to what can be achieved by gobbling up everything from the past. Offering acupuncture for the eyes, it's full of the pinks, oranges and super-sharp angles familiar from Ren & Stimpy cartoons, as well as source material such as the credits for TV's Bewitched or the background paintings created by Warner Brothers artists such as Maurice Noble and Philip De Guard. Bigger names have also been embroiled. At night, Dean's turquoise warehouse has three glowing, gold rectangles where the door and windows should be. Just as in Edward Hopper's Nighthawks, colours themselves are endowed with feeling. The action sequences in the Maine forest work, too. When the Iron Giant jumps into a lake, causing jubilant- green waves to send the world rushing backwards, we could be back in the overwhelming, heart-stopping world of Bambi or Snow White.

Of course, Bird doesn't get everything right, especially towards the end when the Iron Giant is finally cornered by Kent and the US army. Where Ted Hughes' anti-war message was subtle, this young man positively beats us around the head with the idea that killing is bad.

What's gone before, however, isn't so easily erased. One particular exchange sticks in the mind. The Iron Giant, flipping through Hogarth's comics, espies a cartoon called Atomo. "Oh, he's a metal menace," says Hogarth blithely. "He's not like you, you're a good guy." A few scenes later though, much to the giant's horror, Hogarth addresses him as "Atomo" - for the purposes of a game, you understand.

That kids are amoral little creatures - effortlessly switching between compassion and cruelty - is one of many "truths" you can take away from this film. The Iron Giant can do happy and shiny, but it's also got a sharp and rusty edge.