Suggest me a book where people and/or the environment are deeply "off."

I'm looking for a book where someone moves to a new town (or even stays where they are) and everything seems off. Weird vibes, people don't act "right," just really unsettling. It could be a horror book, suspense, whatever.

The main character can be descending into madness, or something really could be weird. I just want a story where the main character is confused, weirded out, and uncomfortable.

Thank you!