From the beginning of his career, when he reworked Ingmar Bergman’s The Virgin Spring into The Last House on the Left, one of the nastiest (and smartest) exploitation horror films of the 1970s, the director Wes Craven had the unique ability to reconcile high-minded ideas with low-down genre kicks. In person, he had a professorial air because he was once, in fact, a professor, teaching English and the humanities at various north-eastern colleges before picking up a 16mm camera. He would turn The Hills Have Eyes into a cannibalistic shocker that doubled as a stark class critique and give the villainous couple of The People Under the Stairs the unmistakable echo of Ronald and Nancy Reagan. He understood as well as anyone how horror could be a vessel for larger themes, so long as it delivered the goods. Forty years ago, Craven hopped aboard the slasher movie trend that had started with Halloween and Friday the 13th and transformed it to his own typically shrewd and thoughtful ends with A Nightmare on Elm Street. (Which he would then deconstruct in Wes Craven’s New Nightmare and piece back together in the Scream franchise, as if following an ingenious long-term course he’d set for himself.) Craven was not the first film-maker to imagine a dreamscape that infiltrates the real world – the random appearance of a goat in the film was his hat-tip to Luis Buñuel’s infamous, surreal fake-doc short Land Without Bread – but his boogeyman isn’t some dead-eyed, sociopathic monster. He’s the ghoulish sins of one generation being inherited by another. But let’s not get ahead of ourselves. Before Craven exposes the rot underneath a seemingly idyllic suburban community – like Haddonfield, Illinois, in Halloween, his Springwood, Ohio, was midwest by way of SoCal – he introduces the boiler room where a teenage girl, stuck in a hyper-vivid nightmare, barely escapes a phantom menace who has welded together a glove with four razor-sharp blades for fingers. When she wakes screaming, it could be written off as a bad dream were it not for her shredded blouse. (“You got to cut your fingernails or you gotta to stop that kind of dreaming,” her mother tells her, unhelpfully.) It turns out she’s not alone. Following the Halloween template once more, Craven offers a virginal Final Girl in Nancy Thompson (Heather Langenkamp), who’s sort of the designated driver type, tolerating the advances of her boyfriend (a then unknown Johnny Depp) while making sure her more sexually accommodating pal Tina (Amanda Wyss) gets through a session with her horny suitor Rod (Nick Corri) OK. It turns out that the teens have their nightmares in common: they’re all being stalked by a razor-gloved man named Fred Krueger (Robert Englund) with a burned, disfigured face, a ragged red-and-green-striped sweater, and an old fedora. When Tina doesn’t survive a dream, Nancy’s policeman father (John Saxon) steps in to arrest Rod, but takes a while to come around to her insistence that the perp is more metaphysical than usual. As a concept, a sinister ghost that attacks people in their sleep remains exceptionally effective and elastic, both for how his victims share the experience and try to keep each other alive, and for how film-makers such as Craven can go wildly abstract with the staging. Dreams can go anywhere and go anything, after all, and Krueger isn’t bound by the laws of physics: you can’t run away from him and that famous sweater doesn’t keep from stretching his arms like Mister Fantastic. To that, Craven adds some of the most memorable shock sequences of the slasher era, such as the geyser of blood that erupts when one victim is sucked into his bed or a staircase that morphs into a mushy tar pit. (The modest independent budget had to include a line item for 500 gallons of fake blood.) Langenkamp makes for a fine Scream Queen, earnest and resourceful while also seeming like an actual teenager, rather than the obvious adults that tended to turn up in films of this era. (The actor was actually 20 at the time, making the line: “God I look 20 years old” after she emerges from a particularly harrowing dream a funny in-joke.) But Craven raises the moral stake on her, too, with the revelation that Krueger once existed in the real world as a child murderer until the townspeople, furious about his release on a technicality, burned him alive themselves. Their vigilante justice – a secret some of them, such as Nancy’s alcoholic mother (Ronee Blakley), have destroyed their lives to keep – is visited on their innocent children from beyond the grave. That piece of A Nightmare on Elm Street sounds like a dark folktale from centuries earlier, but Craven brings it roaring into the 80s, reinforced by the creepy mythos in a nursery rhyme sung by girls skipping rope. (“One, two, Freddy’s coming for you … ”) Though Craven doesn’t allude to any specific event, the generational tension in the film feels evergreen, given how often children have to shoulder the burden of their parents’ catastrophes. Even as proof of Krueger’s identity is snatched from the dream world, the parents still have trouble confessing the truth, partly out of shame and partly out of a misguided instinct to protect their kids. And that’s the Craven touch. A Nightmare on Elm Street doesn’t necessarily need to be more than a horror film about violent dreams puncturing reality – there are eight more of them, in fact – but he adds thematic layers and visual punch that make the film much smarter and more enduring than it might have been. His Freddy Krueger wreaks havoc in the mind, but he lingers in the conscience, too.