Do you know the book I'm looking for?

Question

The story takes place sometime in the late 1800s/early 1900s. A man comes home to find all of the staff in his house unconcious or missing, and when he reaches his study, he finds that his wife has been taken captive by a white-haired vampire. The vampire wants his assistance in solving a case of who has been killing the nearby vampire population off. This vampire asks the main character for his help because the main character was apparently a spy at one point, and was good at getting to secret information. I think the story may have taken place in England. It may have a sequel.

Answer 1

Those Who Hunt the Night by Barbara Hambly.

Answer 2

Is it "The Lily White Men"? Someone else is looking for the author. Good luck.