The V V Agency, by Mike Befeler
Imagine a dash of Philip Marlowe wrapped in an urban fantasy. The V V Agency is a paranormal mystery that spoofs the PI subgenre and introduces the transvictus—a unique shape shifter. Van and Vanna run a detective agency, but clients never see them together for a simple reason. A sexual encounter transforms one into the other, and nudity renders them invisible. This presents some interesting dilemmas for his and her love lives, but gives them a distinct advantage when doing detective work. In this, the first book in the series, Van and Vanna take the case of a woman suspected of killing her husband.