Hallowed (The Guardian Series, #3)
After the decisions Sophie's had to make, she's ready to end Akeldama once and for all. That demon Queen has made everything go wrong in her life. Her boyfriend, Tristan, hates her because she's harboring a demon in her body and the people of the Society avoid her, expecting her to spit fire and devour them all.
With their new mission, they have to go into the demon realm, not knowing what they'll face or if they'll even live through it. The last person they expect to see saves Sophie and Kendra from being kidnapped and allies come from the most unlikely of places.
A new enemy emerges, one more powerful and dangerous than Akeldama could ever be. To save the world, the universe, and everyone she loves, Sophie may have to give up her own life. Can she make that decision and leave everything and everyone she loves behind?