Going down to Dunwich
The man crashes through the door, flees into the night, manages to escape. The woman trails him. One of the pursuers shoots her in the back. As she lays on the grass, crawling, still trying to get to safety, they cover her in gasoline then set her on fire.
That's the start. You get a few minutes of peace before, less than 15 minutes in, The Void becomes flesh-rending, sanity-shattering, Whateley-impregnating unhinged.
It's revolting. It's hellish. It's The Fly and Hellraiser and The Thing and all the best Call of Cthulhu sessions, brought together by the Prince of Darkness.
A horror fan's Christmas movie.