Curse of the Fly opens with a young woman, Patricia Stanley, escaping from the mental hospital in which she has been confined ever since the death of her mother some years before. Dressed only in her underwear, she smashes through the window to her ground-floor cell and disappears into the night in her underwear. She meets up with a passing motorist on the road a while later, who turns out to be Martin Delambre (George Baker) who is heading for Montreal. Patricia decides to go with him, and when the time comes for Martin to return to his lab out in the country, she decides to accompany him there as well. As it turns out, Martin and Patricia get married before leaving Montreal.
Patricia keeps quiet to Martin about her escape from an insane asylum, not knowing she can expect some unpleasant surprises from his private life. Being a Delambre, his "research" involves a teleportation machine, something that had not proved good for Andre and Philippe Delambre in the previous two films. And the legacy of their research is that Martin ages prematurely if he does not inject himself periodically, thanks to Philippe Delambre retaining some fly genes in his DNA, even after he had restored back to apparent normality at the end of Return of the Fly, which have passed on to his descendants. As a result, Martin's body ages as rapidly as a fly's, by which standard he should have died in infancy. The drug he takes controls this accelerated aging, but if he misses a dose, the aging catches up to him in minutes. Little wonder Martin keeps this from Patricia.
Martin and Patricia arrive back home at the Delambre mansion in whose basement a lab is secreted where they continue the family's work on a teleporter. The present model succeeds in teleporting people back and forth from Martin's lab in the Quebec countryside to one in London, where his father Henri (Brian Donlevy) and brother Albert (Michael Graham) are based. The problem is that anything living that enters one teleportation cabinet leaves the other mutated. Henri got away with a skin deformity similar to a huge scar on his last trip, though he insists on keeping this from Martin and insists his trip was a complete success. Previous volunteers were not as lucky, as is later revealed. The equipment Martin picked up in Montreal was meant to sort out this problem.
The day after arriving at the Delambre mansion, Patricia finds herself in the backyard while hiding from Police Inspector Ronet, who is investigating her escape from the asylum. While Henri and Martin attempt to convince the detective that Patricia is a Delambre now, and that the asylum will thus have to go through them in order to re-commit her, Patricia herself stumbles upon a row of locked stables, each of which contains some hideous creature. These are the previous volunteers, the teleporter having left them deformed, semi paralyzed and even apparently brain-damaged. Most of these creatures had once been colleagues of the Delambres, but one, the young woman (Mary Manson), had been Martin Delambre's first wife, Judith. Patricia faints at the sight of them and, when she comes to, her husband and father-in-law try to convince her that her faint was caused the stress of Ronet's surprise visit, and that her encounter with Judith and company was just a nightmare.
Patricia goes on seeing things she shouldn't, especially since the housekeeper lets the deformed Judith out at night to play the piano (she had been a concert pianist), the sound of which attracts Patricia like a moth to a flame and is confronted by the mad jealous/ vengeful first wife, or what she has become. Meanwhile, Ronet checks into the background of Patricia's new family, eventually learning the whole sordid story from the now-retired Inspector Charras (Charles Carson), who had been in charge of investigating the death of Andre Delambre in the original The Fly. It becpmes clear to him that Patricia has embroiled herself into a dangerous environment. Meanwhile, Henri and Martin are suspicious that things are closing in and decide to take drastic action; a move that seals both their grisly fates.
Made five years after Return of the Fly, the film is an unusual second sequel to 1958 original. Or maybe that should be post script, as Curse of the Fly has an entirely different flavour from the first two and stands up very much on its own. This is partly due to the fact that this is a British made sequel to a pair of American films. Though ostensively set in Canada (as the first two were), the English landscape is prominent throughout the film, while George Baker's RADA trained mid Atlantic accent fails to disguise his British credentials.
These quibbles aside, this little known sequel is actually a fine film and arguably the best of the original The Fly films. One of the reasons it gets overlooked is the fact it does not actually feature a man size, half human, half fly hybrid, just its legacy left in the Delambre's DNA lineage. But then, it was such a creature that is now considered the weakness of the first two films in terms of logic; the question Cronenberg asked when approaching his 1986 remake was "Where did the extra atoms come from?" So instead he came up with the idea of the teleported merging the fly's DNA with the human host, and said human slowly mutating afterwards. It is from Curse of the Fly that the gene splicer idea was initially proposed, thus underlying its unaccredited influence.
It is a pity the Curse of the Fly has been largely forgotten, overshadowed by its two Hollywood predecessors. It is a superior film, with better scripting, direction and some haunting photography. The opening sequence, where an asylum window shatters outwards in slow motion and Patricia, dressed only in white underwear, escapes from the oppression of a dark mental institution into that an oppressive, consuming night time landscape; escaping into a dark unknown that offers only more secrets and dangers.
Much credit must to the much underrated director Don Sharp, whose crisp direction lives up to his name. Originally from Australia, Sharp carved quite a healthy career as a jobbing director and sometimes actor. He had previously directed one of Hammer's classier horrors, Kiss of the Vampire in 1962. As second unit director, he choreographed the high flying speedboat chase in the 1971 thriller Puppet on a Chain, which set the standard for speed boat chases in subsequent James Bond films. He also directed a superior version of The Thirty Nine Steps in 1978, which stuck far more closely to the John Buchan novel the celebrated 1930s Alfred Hitckcock adaptation.
Plot wise, screenwriter Harry Spalding draws on that favourite gothic standard, Jane Eyre, a text that previously provided the archetype for Val Lewton's I Walked With a Zombie. Martin Delambre as Rochester, Judith as Bertha Mason. There is also a flavour of Daphne Du Marier's Rebecca with the Delambre's housekeeper, like Mrs Danvers before her, remaining loyal to her previous mistress and ambivalent to the new one. Thus Curse of the Fly also differs from its predecessors in its gothic undertones, further heightened by sharp black and white photography.
The only puzzling thing about the film is that Harry Spalding's screenplay seems unable to remain within the chronology of its back-story, or rather that of the previous two films. Henri states that three generations of Delambres have devoted their lives to the teleporter project, which would seem to make him the son of Return of the Fly's Philippe. But when Charras (who would have to be over 100 years old if Henri is Philippe's son) tells Ronet the story of his involvement with the Delambres, he seems to merge the events of both earlier movies into a single incident, making Martin and Albert the third generation, and Henri the son of an Andre-Philippe character whose history more closely resembles Philippe's than Andre's. Or maybe Henri is Philippe, having changed his forename since his mis adventure in Return of the Fly. That explanation actually makes the most sense.
Curse of the Fly deserves a lot more than its reputation as a forgotten sequel. It has stood the test of time far better than its two ascendants, with classier production values and scripting. In fact, this is a "sequel" that does not actually need the previous two chapters and would have arguably benefited by being completely estranged from them. It has cult film written all over it, so grab the DVD and help get it re discovered.