Fingersmith novel by Sarah Waters

I have a question about a plot twist, do spolier tags work here? I here there is a book-dropping plot twist in the novel but I don’t know what it is yet and do not want to know. Maybe I don’t need spoiler tags. I have read the 1st 150 pages or so, does the twist come after that? Because if it is before, not much of a twist at all.

Yes or no answers only please. Years ago when I saw The Sixth Sense, about 6 months after it came out, either Siskel or Ebert were reviewing the best movies of the year, and they didn’t want to give it away. I think it was Ebert who said something like, "it wasn’t like “I woke up and it was all a dream’” . About 20 minutes into the movie, I knew exactly he meant and it spolied it for me.

Apparantley no one who has read this thread so far has read the book, but now the question is moot. I just got to it and it is a good one. Loving the novel. How to describe it? It’s a Gothic Dickensian type story with a lesbian protagonist.