One Less Warlock — Judith Post

Babet Spellbound has helped River City detectives with cases before, but when Prosper (a Were detective) asks her to use her witch powers to get them inside the most powerful warlock's house in the city--(because he's dead, but his wards aren't), Babet's thrown into a locked room mystery. She ends up interviewing a succubus, a vampire, and a community of women who don't welcome outsiders, before she learns the truth.