Our cinemas are presently teeming with transformation, infested with the umpteenth spawn of Stan Lee, Marvel and DC - underwhelming Spiderman, the Avengers ad nauseam - so it is perhaps worth having a quick spew. Comic books give us transformation, clean, wreathed in steam and colourfully costumed, but the flip side of such adolescent power fantasies is the disgust of mutation; dirty, gooey and possibly fatal.

David Cronenberg’s The Fly begins with Howard Shore’s wonderfully bombastic B-movie score striding through the titles and immediately places the movie in highly strung melodramatic territory. Cronenberg’s gore-fest was based on the 1958 black and white horror film, which itself was based on a George Langelaan short story published a year earlier in Playboy and was directed by Kurt Neumann and scripted by Shogun author Jim Clavell. Cronenberg’s up-to-date reimagining (long before the horrific verb ‘reboot’ had seen the light of day) was an unexpected critical and commercial hit on its release in 1986. It was the film that brought body horror into the mainstream. But gruesomeness aside (only for the moment), The Fly is a chamber piece, a relationship drama, which infests adolescent hopes of transformation with the corrosive vomit of mutation.

Geena Davis is the ambitious journalist Veronica Quaife, who belatedly realises she’s onto a major story when she snags Seth Brundle, a goggle-eyed and socially inept young scientist, at a conference and he takes her home to show off his latest invention: teleportation devices. Completing the ménage í  trois of filigree-named protagonists is Stathis Borans (John Getz), Veronica’s ex-lover and current editor, who at first is sceptical and jealous.

‘I’m onto something big, really big,’ Veronica tells him. ‘What? His cock?’ Stathis replies.

In a sense though, Stathis is right. He’s the hairy truth teller. Everything in the film is motivated by sex, despite Seth’s ludicrous suggestion that his invention has been spurred by the fact he got motion sickness on his tricycle. This is a B-movie horror plot complete with a monster, a mad scientist and a spunky girl reporter, but somehow when it was being teleported from 1958, a tiny relationship drama must have got into the machine and the two were fused. Seth is obviously lonely, which explains his otherwise insane indiscretion in blabbing to the beautiful Veronica. He is the virgin of the piece - unworldly and naí¯ve, with his wardrobe full of the same clothes and his ‘cheeseburger’ dinner date invitation. Whenever he steps out of his laboratory, things are going to go wrong, be it drinks receptions or arm-wrestling contests. His relationship with Veronica is immediately intense and swiftly marred by petulant and adolescent jealousies.

Veronica, with her can-do no-bullshit approach, is the mover and shaker. She is the one who seduces Seth, in her own time and on her own terms. ‘You’re cute,’ she tells him, but only once he’s proved his chops as a scientist. She is the one with experience. She has perhaps used sex in the past, having - after all - slept with her boss and decided to stop sleeping with her boss, while keeping her job. Stathis could easily have been taking advantage of his position. He is the sleazy, hirsute chancer, cheerfully sneaking into Veronica’s apartment to take a shower. ‘Was passing… felt a bit grimy,’ he says. Despite Veronica’s protestations, perhaps they are meant to be together. There are sparks in their exchanges, compared to the puppy love Veronica enjoys with Seth. She cuddles Seth and coos about his flesh, like an old lady who steals babies (her comparison!). Seth is like their baby, a troublesome genius who shouldn’t be allowed out on his own and who ultimately longs to be joined to her and be completed by her. Seth (the romantic) wants to consume her totally, whereas Stathis just wants to fuck her.

The goo of the make-up effects is still impressive today, but none of that matters if we don’t care about the characters, as was to be proved by the sequel, which was directed by the make-up artist Chris Walas to make an interesting but ultimately forgettable film. Cronenberg’s success here, helped by several career-best performances, is to drop fully realised characters into the B-movie plot. Seth’s disintegration as a human being is played out tragically. At first, he feels benefits from the experiment gone wrong: super strength, increased sexual performance etc. but soon comes to realise that it’s a disease, a kind of cancer. His mutation isn’t a clean Peter Parker transformation. To be fair, The Amazing Spiderman does give Parker some sticky moments, but they are more for comic effect than fuelled by body disgust.

Seth is not simply turning into something. That in itself wouldn’t be all that bad. Waking up one morning to find yourself a giant cockroach is amply better than waking up one morning to find yourself a rubbish mix of cockroach and man. The speed of Seth’s deterioration and his desperate attempt to retain some semblance of humanity even as he becomes Brundlefly give the film something like a tragic grandeur. Veronica’s disgust and loathing, as exemplified by her maggot dream, is tinged with pity. Stathis, finally, is also transformed. He becomes the hero of the piece, albeit an ineffective one, trying to protect Veronica and, as a consequence, suffering his rival’s jealous bile.

In the end, the only fatality of the film is Seth himself, who to some extent achieves his ambition of being the first insect politician and retains some degree of humanity (and some call on our sympathy) even in his final moments.

John Bleasdale