Despite its venerable age, David Cronenberg’s The Fly remains the body horror to beat. Viewed today, it’s the film’s purity of purpose that stands out, the relentless commitment to breaking the human body down and putting it back together in all the ways it isn’t meant to be. It’s the platonic ideal of a body horror movie, a perfect 96 minutes of acid vomit and oozing flesh. And oh, the flesh. “You only know society’s straight line about the flesh,” Jeff Goldblum rants late on in the film. “You can’t penetrate beyond society’s sick, gray, fear of the flesh. And I’m not just talking about sex and penetration. I’m talking about penetration beyond the veil of the flesh! A deep penetrating dive into the plasma pool!”

The Fly is a tour de force of disgust, Cronenberg finding new and increasingly repulsive ways to make us look down at our own fleshy forms with slow-dawning concern. Every time an ear falls off or a monkey is turned inside out is a fresh reminder not just of our mortality, but how viscerally unpleasant most of us would find our own innards, how perversely alien our own bodies can seem. But as repugnant as the film gets, as much as it twists the human body into unwelcome shapes, it only serves to hide the fact that the real horror is all in the mind.

Much of the credit for that must go not to Cronenberg himself, but to Goldblum. As scientist Seth Brundle, he brings his unique brand of charm to the film. Brundle is at once awkward and endearing, whether explaining why he wears the exact same outfit every day (he got the idea from Einstein) or waxing lyrical about teaching his computer: “to be made crazy by the flesh.” Like we said, there’s a lot of flesh going on here. Later, after a teleportation hiccup sees him gene-spliced with a house fly, Brundle goes through a dizzying character development. At first he’s all ego, relishing his newfound athleticism and power. Because this is the ’80s, he shows off through gymnastics and arm wrestling. Then, as he slowly morphs into what he calls the ‘Brundlefly’, he spins through horror, disgust, denial, attempts to cure himself, and acceptance, before he ultimately takes a violent turn for the film’s final act.

There are clear parallels to the pop psychological stages of grief, but Cronenberg and screenwriter Charles Edward Pogue add another wrinkle to the mix in the form of the encroaching influence of the fly DNA. It’s one of the few ideas borrowed from the 1958 original (itself an adaptation of a 1957 short story by George Langelaan), but here made immeasurably more interesting. In the ’50s version, the fly mind makes itself known through controlling the scientist’s one entirely insectile arm, leaving poor actor David Hedison wrestling with himself on set. Cronenberg reimagines it as a subtler influence, creeping into Brundle’s decision-making, blurring the lines between compassionate human thought and the ruthless insect mind. As the Brundlefly becomes increasingly erratic during the film’s finale, it becomes harder and harder to tell where Brundle ends and the fly begins, which is exactly Cronenberg’s point. By the film’s end, there’s no point looking for Brundle – he’s long gone. So’s the fly, and all that’s left now is the Brundlefly hybrid.

Then, of course, there’s Brundle’s relationship with journalist Veronica, brought to life with blustering bravado by Geena Davis. She has an instinctive sympathy for the creature Brundle becomes, and is afforded one of the film’s most iconic moments, a nightmare vision of a pregnancy brought to terrifying conclusion, a writhing, squirming, two-foot maggot ejected from her womb. The physical horror of the moment is immediately apparent, but it serves a broader psychological purpose, vividly bringing to life her unshakeable fear that something alien might be growing inside her, that her own body might be turned against her. Far-fetched though The Fly undoubtedly is, the pregnancy brings it crashing home, twisting a natural, often welcome, process into something just as horrifying as any shot of Jeff Goldblum vomiting acid.

The Fly is incontestably revolting, a creeping progression of some of the era’s finest prosthetics, and a horrifying look at the human body slowly collapsing, quite literally falling apart. But more than that it’s about a man losing his humanity, his personality shifting just as frequently – and violently – as his body parts. The greatest tragedy of The Fly isn’t that Brundle dies, or that he becomes a hideous creature beforehand – it’s that he loses so much of himself that he tries to take Veronica with him.

Published 14 Aug 2016