60
The Fly (1958)
(lemmy.nz)
IF SHE LOOKED UPON THE HORROR HER HUSBAND HAD BECOME... SHE WOULD SCREAM FOR THE REST OF HER LIFE!
François Delambre is called late at night by his sister-in-law, Helene, who tells him that she has just killed her scientist husband. Reluctant at first, she eventually tells the police that he invented a matter transportation device and, while experimenting on himself, had a horrific accident that altered the essence of his very being.
It's the trailer I linked in the post. It's gimmicky but I love that, by not showing anything, it's fairly spoiler free. It's great how they did it here and I wish more movies would go this route.