Can anyone recommend me a really disturbing book?

I am a huge fan of thriller and horror. This might be a weird question but I am not looking for something that is really brutal (maybe a bit) I am looking for something that makes you genuinely uncomfortable and questioning own worldviews and reality. Maybe something where you don’t 100% know who really is the villain like in Shining by Stephen King? Maybe something that tries to show how f..ed up society is. I liked „tender is the flesh“ by Augustina Bazterrica even though I found the plot itself a bit… flat? It was still a good book. But I’m Looking for something even more disturbing if u know what I mean. (Please believe me I’m not a total weirdo.)