The Dead Witch - The Pumpkin Spice Tales, #2

Pumpkin Spice--Maine Coon cat and part-time familiar--refuses to let her witch die. But Morwen's birth spell has gone seriously wrong, and now Spice has hours--perhaps less--to break the enchantment before it kills both mother and child. Which is the perfect time for Spice to learn a terrible secret: The Dark Yule is far from finished with her. On that dreadful night, Spice accidentally let someone escape.
Someone whose very presence has awakened another creature. A creature long-hidden and forgotten, in a realm neither here nor there, but desperately clawing its way towards our world... If Spice faces down the monster, she'll lose her witch. If she saves Morwen, the beast will break free-and they'll lose all of Kingsport. It sounds like a no-win proposition, but that's never been Spice's style. She'll get it done, even if it sends her to the underworld. Or-far more frightening-to the hellish caverns far below Kingsport...