In the movie the creepiest part is definitely Zelda, but in the book, definitely the following.
The thought of living your whole life in this kind of subconscious situation, is just unthinkable to me. It may not be as creepy if not read the book up until this point, because otherwise you don't really know what it's made of--if read you've lived through all the evil and darkness of it. I don't know, you tell me how creepy/affective you find this bit if you haven't read the book?
Louis had carried his dead wife down the path leading up to the Pet Sematary and invited Steve Masterson to come with him, wanted to show Steve something. Told Steve that on the way he may hear sounds, like voices, but it's just the loons, down south in Prospect. The sound carries and that it's funny. Just like Jud had told him when he first took Louis there. Steve was tempted to follow but suddenly it was as if something let go of him, he didn't feel the strange pull anymore--quite contrary--and he ran home without stopping. Soon he moved away.