I agree with Vito Veii, this is an excellent series.
Starting with a vampire in the Vatican continuing through Nun with a Gun and reaching the Aesinas Codex, the inspectors main goal is to find and kill vampires.
He is very likeable as you get to know him and has to deal with so many other investigations along the way. It seems to me that his main motivation is revenge, a friend is killed in the first book (a vampire in the Vatican) and everything goes on from there.
Nazi gold in Bavaria, finding the Aesinas Codex and getting it back to the Vatican, finding and killing vampires of course.
A most enjoyable read from beginning to end.
(reviewed the day of purchase)