basically, a Victorian suspense novel that truly had the suspense. in spite of the contrivances of the plot, it was definitely a page-turner and sometimes filled me with a sense of dread (me of all people)
the sympathies and social sensibilities of the author were quite advanced for his time, though the book did suffer from some prejudice toward anyone who was not English
anyway a lot of the first half of the story was...a slow inexorable buildup of dread, and even though you think you can see it coming from a mile away, you really can't