It's in 'Changes', the most recent novel.

This is the same book where he wipes out all the Red Court vampires (who are pretty universally described as Hispanic/Latino). It's a little squirmy when the white main character wipes out an entire group that has been specifically depicted as non-white. One of my more tactless friends swears that if he ever meets Butcdher he's going to ask him why he decided to go with the 'Latino genocide', as he describes it. Meanwhile, Dresden is allies with the other group of people-eaters in the series...you, know, the pale white ones. We've never seen a human/humane Red Court, either, whereas we've seen at least one protaganistic White Court.

I used to like the Dresden Files but boy howdy, does the author have issues.