Visions from the dark side

'Forget it Jake, it's Chinatown.' But Anthony Quinn can't erase his memories of what is arguably the finest film of the 1970s

It's the bandage you can't forget. The private eye follows his nose, and then has it almost lopped off. It's character- istic of the sudden reversals in Chinatown that its cocksure private detective, Jake Gittes, spends the early stages of the movie strutting around in his immaculately tailored suits - "Face it, you're practically a movie star", his barber tells him - only to skulk through its middle section with his nose mummified in pieces of tape as white and thick as a horse's noseband.

That bandage, ugly and unignorable, signalled a shift in the portrayal of movie heroes. The screenwriter Robert Towne took his cue for Chinatown from the hardboiled detective fiction of Hammett and Chandler, and in Gittes's flippant, wisecracking style one hears echoes of an earlier Los Angeles private eye, Philip Marlowe. But Bogart, you feel, would never have countenanced a bandage on his nose. Back then, movie stars could be roughed up, but a manly scar would be their badge of honour. True, James Stewart in Rear Window wears a plaster cast on his leg, and, like Gittes, acts the nosy parker. But his injury was a plot device, a way for Hitchcock to render Stewart immobile and so make the audience complicit in his agony of helplessness. Jake's sliced nose was simply malevolent fun, like a joke moustache scrawled on a woman's face on an advertisement.

By 1974, when Chinatown was released, the detective was no longer a knight in shining raincoat: the snoop was a sneak, a liar, even a sleazeball. Nixon and Watergate had rocked American confidence and made "surveillance" not just lowdown but positively sinister. Gittes was played by Jack Nicholson, an actor establishing a line in sardonic charmers - in Easy Rider, Carnal Knowledge, The Last Detail - who are heading for a fall, or for a slashing by a diminutive thug. That the thug is played by the film's director, Roman Polanski, was a joke they doubtless savoured on set. It was Nicholson who had first suggested his friend Polanski for the job, then producer Robert Evans followed up. As Evans tells it in his delightfully bumptious memoir, the main problem was Towne's script, a convoluted tale about water exploitation in California during the 1930s: "No one understood it - especially me. Just like the title, it was pure Chinese." Polanski recalled in his autobiography that "it simply couldn't have been filmed as it stood, though buried somewhere in its 180-plus pages was a marvellous movie".

Writer and director got together to hammer out a rewrite, and the fights began. Gradually, Polanski wrested control of the picture from Towne, who felt his original story had been betrayed and particularly resented the "ghoulishly bleak climax". Yet between them they must have done something right, because the dark-hued fatalism of Chinatown remains, 30 years on, among the peaks of noir cinema and probably the best movie of the 1970s.

On first viewing you revel in the film's sumptuous surface: Nicholson's metallic drawl and his dandyish threads; the scarlet mouth and perfectly arched eyebrows of Faye Dunaway; and production designer Richard Sylbert's period evocations.

A second and third viewing allow you to sort out the false trails and sly feints of its plot, which, like a Chandler novel, features a little sister and a rich father, though their horrifying connection, long withheld, is more a throwback to Greek tragedy. You will also catch on to the leitmotif of seeing and not seeing, hinted at from the very first line, as Jake asks a distraught client not to chew the Venetian blinds. Optical images recur throughout, tipping us the wink. Jake spies on Mulwray through binoculars, and later through a camera lens. The private eye looks, but he doesn't see, and what he says will come back to haunt him. When Evelyn asks him what he used to do in Chinatown, Jake heads her off: "As little as possible." But he makes the same mistake of trying to save someone from being hurt, thereby ensuring that she is hurt. When he finally beats the truth out of her ("She's my sister - she's my daughter"), he looks stricken, as much by his own unseeing as by Evelyn's tragic revelation.

In the last quarter, the signs become premonitory: Jake examining the flaw in Evelyn's iris; the cracked bifocals fished from the pond ; Curly's wife's black eye. Polanski spurs on the film towards it merciless climax as the tables are turned on Jake and the fleeing Evelyn is shot by a police bullet - through the eye. As her head flops out of the car door, we hear her daughter's rising screams and then fix on the terrible sight of Noah Cross, the robber baron and rapist, trying to shield the girl's eyes with his hands.

This was the ending over which Polanski and Towne fought so heatedly. Towne meant for Evelyn to escape with her daughter, but Polanski saw it differently, as well he might. His life had been stalked by death, first as a boy in Cracow under the Nazis: both parents were sent to the camps and his mother died in Auschwitz. In 1969, his pregnant wife, Sharon Tate, was murdered by the Manson gang in Los Angeles. "Every street corner reminded me of tragedy," he later admitted. Experience and instinct prompted him to reach into the dark: Evelyn would die, Cross would prosper and Gittes would be left to rue his pursuit of "the truth". Polanski's decision was surely the right one. His choice of ending answered not just the mood of the film but the mood of the country, tense with paranoia.

The film, nominated for 11 Academy Awards, won only one: Best Screenplay, for Towne. Towne spent years drafting a sequel, which he also planned to direct, with Nicholson reprising Gittes and Robert Evans co-starring. In the event, all three men fell out, Nicholson himself oversaw The Two Jakes, and the result was one lousy movie. Let's be thankful for Chinatown, a career zenith for its director, writer and maybe also its star. Nicholson won an Oscar the following year for his ballistic performance in One Flew Over the Cuckoo's Nest (1975). But as Jake Gittes he carries himself with such ludicrous self-assurance that one is torn between admiring, despising and pitying him. This duped detective holds the screen from first to last. It's his finest work - by a nose.

'Chinatown' is showing in the Polanski season at the NFT, London, SE1, to 13 May