The Stone Monkey, by Jeffery Deaver
Fourth in the Lincoln Rhyme series by Jeffery Deaver, and a re-read.
The main plot this time involves a group of illegal immigrants from China who are being hunted down by the man who arranged to smuggle them across the ocean. Lincoln and Amelia were already trying to find that man so they end up both searching for him and trying to protect the group he's hunting.
In their personal lives Amelia is dealing with finding out that she has some physical issues of her own that might get in the way of them having kids. Lincoln is still pursing the surgery he was trying to have in the last book, and there's a number of really interesting conversations between him and a Chinese cop about it.