The Monk - Matthew Gregory Lewis

By the end of this book, I could scarcely believe how far the story had gone. If you ever want to see what a real downward spiral looks like, take a look at The Monk. This is a prime example of Gothic fiction, and one of the more sickening tales you'll ever come across (no, really. I was less disgusted by "Titus Andronicus"). 

I was really surprised by how gripping the book was. Many things which were shocking 200+ years ago barely move the dial nowadays, but The Monk holds up. It's still shocking and quite the wild ride. You can really see why it was such a controversial book when it was first printed. No doubt the Catholics of the day did not find it at all amusing.