In a utopian society ruled by the Twelve Guardians, twenty-three-year-old Saskia has been taught to never question those who protect her city, Xantera, from the Monster who prowls beyond the Wall—even when they demand living sacrifices in exchange for this protection. She eats the food they provide her, works the Healing Center shifts they've designated for her, and lives with the partner they've assigned her.

But when Saskia finds a strange necklace left behind by a mysterious patient in her Healing unit, she begins to hear a voice in her head that could change everything.

Smooth, deadly, and masculine, the voice teases and tempts her, igniting embers in the emptiest part of her heart and challenging the beliefs that have been instilled there. Before long, she begins to suspect the necklace has connected her mind to the Monster who prowls outside the Wall—a Monster who is nothing like she expected.

And he wants her to let him in.