The Isis Collar

Celia Graves was once an ordinary human, but those days are long gone. Now she strives to maintain her sanity and her soul while juggling both vampire abilities and the powers of a Siren.

Warned of a magical "bomb" at a local elementary school, Celia forces an evacuation – but not everyone gets out in time. Oddly, the "explosion" seems to have no effect, puzzling both Celia and the FBI, which is secretly (and magically) investigating. No effect, that is, until two weeks later, when a strangely-persistent bruise on Celia's leg turns out to be the first sign of a magical zombie plague.

Helping the FBI track down the source of the plague isn't Celia's only concern. Her alcoholic mother has broken out of prison on the Sirens' island; her ghostly little sister has possessed a young girl; one of Celia's boyfriends, a powerful mage, has disappeared; and both of her boyfriends have been exposed to the plague.