Original Sin - Plot Points and Questions

There are a few plot points and interesting questions I have for the readers.  For one, who did you see as the murderer?  Was it who James reveals in the end, or did you have someone else in mind?  and why?? Number Two- I personally found the storyline about Frances' childhood and her fear of the underwater tunnel, along with the relationship she has with James deWitt, to be some of the strongest plots in the novel.  Besides building a murderer who is out for the simplest revenge, the murderer also manages to play devil's advocate to others with the poisoned pen letters to the members of the Peverell Press.  For Frances, the murderer is able to make Frances face her fear and let go of the person she has been hiding in.  The murderer turns out to be an angel in a way for her and this strange twist of plot is one of the best I have ever read.  This just proves James' abiltiy to evoke powerful and passionate characters.

What are your thoughts on this part of Original Sin??