One night in the countryside near Montreal, a young woman clad only in her underwear escapes from a mental institution and flees into the darkness, following the road until she is nearly run over by a car. She is Patricia (Carole Gray), and she has been placed in the asylum due to a trauma in her past which she has not gotten over, but now she's out and meeting the driver of the car may be her biggest mistake so far. He is Martin Delambre (George Baker), and as he drives her away, they agree not to ask one an other about their circumstances - for him, being a scientist with a secret or two is best kept quiet about.
Especially when the scientist is falling in love very quickly with his passenger, to the extent that he doesn't hand her into police or try to find out where there's someone she might know who could help her, but goes and steals clothes for her from a washing line and checks her in at the hotel where he's staying. But then, making mistakes would appear to be what the Delambre family were all about in this, the belated last entry in the trilogy of movies based around The Fly, the classic short story which spawned the semi-classic horror of the fifties, and a couple of sequels that don't often get discussed. British-created Curse was not seen much since 1965 except on television, but left an impression on some.
This was mainly down to director Don Sharp and his team following the lead of the initial effort and aiming to disturb, so the full implications of experiments going wrong were given full rein here as the Delambres have not learned their lessons from both of those not exactly happy excursions into teleportation and are still at it, now with a booth in England and another in Canada. They have been trying to send people across the Atlantic, all for wholly altruistic reasons - transporting essential supplies across the world in the blink of an eye, for example - but as is the way with mankind dabbling in God's domain, in the movies at any rate, it's all set to go horribly wrong before the end credits.
In fact, it's all gone horribly wrong before the opening credits, for one of Martin's secrets is that if he does not inject himself with a special serum he turns all crusty thanks to a premature ageing condition: actually thanks to makeup which even by contemporary standards was pretty grotty. But the oblivious Pat is smitten with him and vice versa, so after a week in each other's company they're married and headed over to the country mansion of the Delambres' where she gradually finds out what we've been suspecting, which is that there are some rum doings going on there. For a start, someone appears to be kept in the stables, and after she gets a glimpse of one she's terrified no matter Martin's excuses, making her worry all the more that she's going mad after all.
She's not going mad, it's just that everyone, including Martin's driven father (top-billed import Brian Donlevy), would prefer to have her believe she's mentally unstable rather than tell her the awful truth. That being the nature of these experiments and the terrible effects they have on their subjects, bad enough if they'd been on animals but the concern here is human vivisection as the Delambres have been merrily warping the forms of their volunteers to render them into barely human and violent creatures. While David Cronenberg would take the notion of these things going wrong and run with it to stomach-churning effect in his remake of The Fly, it was apparent in this film that they thought that was a very good idea as well, and although there's not too much gore they were definitely attracted to making the audience uneasy and even disgusted with the possibilities a harrowing teleportation accident could have - see the first Star Trek movie for more. So in that lightly nauseous and fairly suspenseful fashion, Curse of the Fly was indeed memorable, if rather basic otherwise. Music by Bert Shefter.