At The Advent Of Dusk (Master Chronicles #0.5)

1962. Chicago.

Gideon Keel is the most feared vampire in the city. Nobody dares to stand up to him--until somebody does... When his path crosses that of the charismatic civil rights activist's, Gideon faces the first person in more than sixty years to threaten his existence and live to tell the tale.

Mary Straughn is beautiful, driven, and most of all, determined not to let anyone--even a vampire--hurt the people she is trying to lead into a better life. He knows he should kill her. Yet, when she needs help tracking down the vampires responsible for murdering two children, he finds himself agreeing to search the city for them. And all he asks in return is for one night alone with her...