This evokes memories of Wilkie Collins (insanity and opium) and Daphne Du Maurier's "Don't Look Now" (hints of the supernatural in decaying Venice) although I have to say that both of these authors "did it better". The apparently well-researched and intricate plot contains many sinuous twists with some melodramatic scenes which sit rather oddly between rather dry explanations of the role of the banking system in the survival of late C19 societies - quite prescient since the book was first published in 2008! The structure is also unusual: three separate sections, successively set further back in time, with a different narrator and location, but serving to fill in further gaps to explain the life and death of the financier John Stone. This "back-to-front" approach inevitably saps some of the potential tension and suspense.
Although I understand why this book has been so highly praised, it does not work for me. This is not because many of the characters are not very likeable, and tend to be snobbish, class-conscious and anti-semitic - this is all part of the period covered. One reservation is that the large number of characters paraded before us tend to merge together - it is hard to relate to most of them, and to identify and recall the significant "clues" they may drop. Too much of the tale is reported via these characters, often in implausibly fluent speech. This brings me to the point that, despite their ( I think we are meant to find) very different personalities, the three narrators all use the same "voice": a very articulate, rather cynical, for the most part bloodlessly objective, tone - the author's? And although I think I was meant to be captivated by Stone's wife Elizabeth, I found both her and Louise Cort to be thoroughly unconvincing. Whenever the plot takes a romantic turn, the at other times erudite writing becomes squirmingly Mills and Boonish. Although the plot does hang together, the "denouement" at the end of Part 1 is a bit rushed and confusing (all that stuff about Bob, I mean Jan the Builder). In general, every section seems to have a long, slow, wordy build up to an unduly compressed finale.
I think it would have benefited from a ruthless pruning and editing. Perhaps the huge success of earlier work places the author above the requirement to do this.