Ghostwalk, by Rebecca Stott

I can't say that I'm crazy about this book, but I did read the whole thing. It is, in part, a ghost story that involves Isaac Newton and some interesting (I'm not at all sure how accurate) information about his personality, and his involvement with alchemy. The book takes place, almost completely, in the 21st century rather than the sixteenth, but Newton and shades of the past figure prominently.