Sometimes conventional wisdom is true: there has been no greater original screenplay in the last 50 years than the one Robert Towne wrote for Chinatown. None more elegantly plotted and politically charged, none more literate and historically evocative, none more pungent in its hard-bitten dialogue and sophisticated in its play on noir archetypes. It’s never easy for a writer to get credit over a director – especially a director as skilled as Roman Polanski at peak form – but Towne’s voice reverberates strongly through a film that perfectly intersects Old Hollywood glamor with New Hollywood revisionism. It’s one of the decade’s true benchmarks. It is also one of the most unremittingly bleak statements on How Things Work in America, where vast swaths of civilization are moved on the whims of powerful and unaccountable men, who can rest comfortably knowing their sins won’t be scrutinized on Earth. Yet the film goes down easy, thanks to the art deco seductiveness of its late ’30s Hollywood setting and a lead performance by Jack Nicholson that tucks a dogged, quixotic sense of justice behind a veneer of unimpeachable cool. His character may be a sarcastic private eye who gets paid mostly to snap photos of adulterers in flagrante, but Nicholson plays him with a hidden nobility. He’s going to follow this case to the end of the line, even though he has the hard experience to know it won’t lead him anywhere good. Every small piece of Chinatown fits together. An opening scene where a client (Burt Young) flips through racy photos of his wife having an affair pays off in the third act when Nicholson’s detective, Jake Gittes, asks for a favor to settle his debt. (It’s also an introduction to Towne’s dialogue. When the client reacts too dramatically, Jake quips: “You can’t eat the venetian blinds. I just had them installed on Wednesday.”) After a woman introducing herself as Mrs Mulwray (Diane Ladd) asks him to follow a husband she suspects is cheating on her, it’s just another job for Jake, who’s used to operating well below his deductive capacities. But this new case brings out his best. Poor Jake gets played for a sucker. It turns out that Mrs Mulwray isn’t really Mrs Mulwray, but part of a scheme to smear Hollis Mulwray, the chief engineer of the Los Angeles department of water and power, who firmly objects to a multimillion-dollar plan to build a structurally unsound dam. Hollis’s real wife (Faye Dunaway) is enraged to discover Jake’s photos surface in the newspaper and the plot thickens further when Hollis is found dead from a supposed drowning accident at a reservoir. With the city in the middle of a historic drought, large quantities of water have been diverted from reservoirs at night to some locations and not others, and real estate records are revealing a grand, insidious scheme at work. Jake can’t help but get enmeshed in the details, not to mention the twisted life of the femme fatale who’s leading him into it. Loosely inspired by the water wars that shaped southern California in the early-to-mid-20th century, Chinatown brings startling urgency to the sort of lightly attended public planning meetings that can enrich some and bankrupt many. As one of the most sterling examples of LA noir, the film makes a Goliath out of City Hall, where decisions about the apportionment of resources to a “desert community” are too important to leave to the public. In a savvy piece of casting, John Huston plays Noah Cross as the ultimate behind-the-scenes player, a Mephistophelean architect who stands 6ft 2in and seems much more imposing, due to Polanski’s low-angle shots and Huston’s sonorous voice. The scenes between Cross and Jake alone are a dazzling battle of wills, because all of the confidence and swagger that Nicholson projects so naturally withers in Huston’s presence. During their meetings, Cross keeps mispronouncing Jake’s last name – he calls him “Mr Gitts” – which is probably a deliberate strategy to make Jake seem unimportant, but could, in fact, reflect a genuine unimportance to him. “You’ve got a nasty reputation, Mr Gitts,” says Cross. “I like that.” But their similar reputations do not make them the same: Jake is a good enough detective to discover every last one of Cross’s dark secrets, but there’s nothing he can do about it. That’s how real power works. Though producer Robert Evans chronically gobbled up more credit for his time at Paramount Pictures than he deserved, Chinatown stands out among 70s productions for its impeccable grandeur, which not only brings the city to era-specific life but suggests the tectonic forces that truly shape it. From the Catalina Island estate off the coast where Cross does his scheming to the parched orange groves of the north-west valley, the film maps a geography of wealth and want over a city that appropriately scaled up. To a certain extent, Jake could be the gumshoe in any B-grade detective story, following leads wherever they take him, but if Evans had skimped on the budget and top-line talent, the film wouldn’t have the same impact. Chinatown is part of a great continuum of California noir – informed by Raymond Chandler and Dashiell Hammett on one end and followed by work like LA Confidential and Inherent Vice on the other – where crimes of passion are often rooted to municipal rot. At best, reluctant heroes like Gittes can only discover how a city like Los Angeles or San Francisco really operates, just enough to affirm or deepen their cynicism. “Politicians, ugly buildings and whores all get respectable if they last long enough,” sneers Cross at one point. It’s as if he can already see the bronze statue that will one day be erected in his honor.