'How I Live Now' by Meg Rosoff.
This is actually a book written for teenagers but I think it works well for adults too. This is a book set slightly in the future and features a young American girl who comes to visit her English relatives. The visit does not go as planned but I will not say any more. I found tis book surprising, it was not how I thought it was going to be.
I picked the book because whilst it is not a perfect book, I think it is interesting and thought provoking and was certainly different to what I would normally read.