Strongest Souls by Riley Onyx

The castle at the center of Under is no fairy tale palace.
The Queen of Under seized power by being the most brutal monster. She’s pulled more people through than her predecessor and the rumor is she’s been searching for someone.
Me.
Now I’m here, she doesn’t want to let me leave. She locks me up and assigns her meanest guards to stop me. While my pack defends me, the fighting is chipping away at their souls, and I can see the glimmers fading. I have to save them.