It's a brilliantly written and conceived book - a story told by the various protagonists, from their points of view, in their voices. And the story is a wonderful yarn of old-fashioned evil pitted against old-fashioned good, but in such a way that it never deteriorates into bombastics or sentimentalities. Evil is truly evil and good isn't too squeaky clean either.
From 18th century Venice to Arequipa in Peru the narrative takes us back to a time we can't quite imagine, and on the way we learn quite a bit. 'The Book of Human Skin', with dark humor, covers many 'sins'--from saintly anorexia to dangerous quack medicines of the time.
The baddie, of course, collects very special books covered in a very special material.
If you loved the 'Three Musketeers' et al, I recommend this book highly.