Guardians, Protectors, Witches. The titles vary species to species, but they all mean the same thing: an individual with a Spark of power and a purpose. Every Spark has an ignition point where their power goes from everyday useful to world-changing strength. Some Witches die in their spark-point.

Penelope Williams is angry. A daughter of conservative parents, her Witch power coming to light reveals a hidden family history of a Salem survivor and power buried for generations. Disowned by her family, she lives as a ward of the Witches, studying and working far from Earth. She ignores the pain of her family's abuse, shoving aside the trauma of rejection and betrayal. Penelope throws herself into her work and her power, her abrasive attitude pushing anyone but demons away. Even in the midst of her pain and outcast life, people from several species choose to make friends with her. The one that surprises her the most is the demon Ikthiel.

At the Edge of reality, a threat looms twisting the nature of space and time, encroaching from the space beyond the universe. Despite warnings from Ikthiel, she cannot focus on the coming threat, instead focusing on her studies and striving to find her power's purpose. But threats cannot be ignored forever. And Penelope faces what could be the answer to all her questions.