Firestorm — Nancy Holzner

They call it Deadtown: the city's quarantined section for its inhuman and undead residents. Most humans stay far from its borders--but Victory Vaughn, Boston's only professional demon slayer, isn't exactly human...

When Vicky allowed an ancient goddess to possess her, she had no regrets--it was the only way to protect the people she loved. But now Ceridwen, locked in a power struggle with the Hellion that long ago claimed Vicky with its mark, refuses to leave. Both beings believe controlling Vicky is the key to winning the coming war for the human realm.

Despite the forces pulling her apart, Vicky needs all her wits about her. The demons of Hell are growing bold and she can barely keep up with the attacks plaguing the city: sirens in the Mystic River, goblins snarling traffic on Storrow Drive, imps tearing the gold from the State House dome. As the signs of war multiply and Hell threatens to overrun its boundaries, Vicky finds herself torn between her duty to save the world and her desire to save something of herself...