Michael Gruber? I think that he has written around seven mysteries/thrillers. I am currently reading one about the discovery of a Shakespeare manuscript and by page 80 I still don't know what the mystery is, but the book jacket says that someone gets killed.
I assume you're referring to The Book of Air and Shadows, which I've read, though I haven't read anything else by Michael Gruber.
If I recall correctly, there was a ton of flashing back to the 17th century in that book, which was awesome for like 100 pages, then got a little annoying. I did finish the book, which is a pretty significant accomplishment for me, but I certainly wasn't inspired enough to read any other book by him.
Oh, and SPOILER ALERT: That Shakespeare guy dies.