Over the years I have tried to remember the title/author of a book I read as a teenager. I have very vague memories of thinking it was good, and every so often something re-triggers me trying to find it.
As a rough guide to time, I was a teenager in the 70s/80s.
The, very few, details I remember are:
One of the (main?) characters is a woman who's blind but doesn't know it. She gets all her "visual" information from people nearby (I think it says her flat is laid out exactly the same as the guy who lives above her because that's what she "sees").
Some sort of demon thing is killing people (in gruesome ways).
Alphabetically the author was fairly early in the alphabet (from where I think it was on the library shelves). Possibly first quarter of the alphabet.