Panther Prowling: An Otherworld Novel. Otherworld, #17

We're the D'Artigo sisters: savvy half-human, half-Fae ex-operatives for the Otherworld Intelligence Agency. My sister Camille is a wicked good witch with three gorgeous husbands. Menolly is a vampire married to a werepuma. And me? I'm Delilah, a two-faced werecat and a Death Maiden. While the war in Otherworld is expanding, so is my newly-renamed PI business. And when our cousin Daniel gets himself in trouble stealing an ancient artifact from the wrong person, he also puts us in deadly danger...
We have to do something while waiting for Shadow Wing's next move, so I've renamed my ragtag PI Agency-Cat's Eye Investigations-and have opened my doors again. Leave it to fate that my first client is our cousin Daniel, a topnotch cat burglar. He's stolen a rare and valuable weapon, and now finds himself pursued by an elusive enemy. My investigation uncovers a ring of ghostly warriors dedicated to protecting the sword, and the soul that is trapped within it.
As my sisters and I try to elude these deadly shades, we begin to realize that the soul trapped within the sword is a far more dangerous enemy-and that he's about to break free from his prison...