Plot Kitty is Plotting!

One day I will get you my pretty. Oh, yes...
I. WILL. GET. YOU.Of late I've read some great books with fantastic plots and some other books that while good, didn't have the fantastic plot I was looking for or it wasn't carried out the why I was hoping for. To me, a perfect book is one that combines deep characters with an intriguingly original plot. 

What YA or MG books have you read with "blow me away" plots? The kind where you're left scratching your head, wondering how the author came up with something so insanely amazing?