So...I am going to have a real problem sticking to my guns about no repeats on this list (especially since I keep picking more than one book).
I've already talked about Harry Potter, The Chronicles of Narnia, All of Tamora Pierce's books, Abarat, and Unspoken, all of which would be contenders for this category. I'm going to go ahead and see if I can pick a standalone novel, so let's see where that leaves me...
I've picked both of these books because
A. Then I don't have to choose between them, and because
B. The less you know about them, the better. It means I can't talk much about them, but I'm hoping you'll take me at my word here that if you love INSANE plot twists, both of these books are definitely for you. (And on a sidenote, I've discovered almost all of my favourite standalone novels are adult fiction. There's like two that aren't. Is this because almost all of YA is series now? Uncertain...)
If you like gothic feeling books, I couldn't recommend The Thirteenth Tale more. I cannot talk enough about how in love I am with this book. If you read her book Bellman & Black and hadn't read The Thirteenth Tale, please please please don't judge her writing by that book. (Or rather her ability to write things that are heart racing, absorbing, and have a plot. Her writing is beautiful even in Bellman & Black, it just didn't actually make anything happen). I don't know a single person who didn't love this book. (And these are all reviewers or authors whose opinions I value greatly. Also sorry not sorry, I was a total creeper and totally checked out if we loved the same books. What? It's important to know!) Basically, the writing in this book is just beautiful (and we know how I am with beautiful prose), it definitely has a complicated premise (so if you like your mysteries clear cut and simple, this isn't for you), has a...narrator that is my favourite type (LOVE - it's even like an unreliable narrator getting the story from an even more unreliable narrator. IT'S THE BEST.) and best of all, it's all about books :) (Also if you liked The Thirteenth Tale and haven't checked out The Shadow of the Wind - and vice versa - you totally should.)
The Double Bind is no less complicated than The Thirteenth Tale, but it's a very different sort of mystery. But again, I can't say how. I will say it is just as...dark, but in a more graphic way? This was my very first Chris Bohjalian novel, and remains my favourite. If you've read any of his novels, I will say that they are all very different, and this one is definitely in a category all on its own, so if you've read his more popular books (like Midwives) it is nothing like them, and you shouldn't bring any conceptions of his style of story telling from those. Even more than The Thirteenth Tale there's just very little I can talk about. Like...there are things that I want to say...I just can't! Because you need to know NOTHING beforehand. Just...can someone PLEASE read this so that I have at least one friend who has read it and I can talk to someone about it? GO READ THIS NOW.