The scariest thing about this movie is that I knew what year to put in the review's title without checking anywhere. The movie itself was just so-so.
And while the movie poster warned "FOR YOUR OWN GOOD WE URGE YOU NOT TO SEE IT ALONE!", it wasn't really designed to be scary. Or even creepy. Just kind of sad (you know, because it's sad when you get turned into a flyman and then your life totally goes to hell).
This is your basic "do-gooder-science-type-tries-to-benefit-humanity-but-destroys-self-instead" movie. Here, brilliant but kindly scientist Andre Delambre has invented a teleportation device, that he first tries out on the family cat. Things don't go well for the cat and so, having no more pets, Dr. Delambre tries his invention on himself. (I know! That's what I thought.)
Well, unbeknownst to the good doctor, a wee housefly has zipped into the teleportation chamber with him. So... as - BZZZT * FWEEEP * BINNDDT - the process completes and reintegration chamber door slowly opens, out steps...
Dr. Delambre wearing an unconvincing rubber fly-head mask and a shiny plastic fly-claw over one of his hands! But, of course, in the movie it's a real fly-head and claw. The Doc has been mushed-melded with the fly (and the fly with him) so they've swapped body parts. (Yes, there is also a wee fly sporting a human head and hand buzzing around the house.)
Now from here, the Doc doesn't go out on a rampage scaring and eating people. He doesn't trap his wife and son in the house and terrorize them. He just spends the rest of the film trying to find the fly with his head so he can try to put himself back together. Reasonable, really.
Well, he can't find that fly, even with his wife's help. (She screamed pretty loud when he showed her his head - that's her on the poster.) And to boot, he realizes his human brain - inside his fly-head? - is slowly turning into a fly-brain and so he asks his wife to kill him by smooshing him under a machine press. And she does.
And that's it really.
TWO BUZZING BRAINS
If you wanna see a scary, creepy AND sad movie, you should get the remake with Jeff Goldblum from 1986. Same Fly-Premise, totally different Fly-Story.