When six-year-old Martha Higden finds a mysterious book in her father's study, she unwittingly summons Erlich, a demon who offers her protection-for a price. Years later, with her father gone and her world turned upside down, Martha uncovers his hidden past as a world-jumper-a traveler between dimensions.

Now, along with her friends Jess and Kip, she must navigate a new life of magic and danger. But the book she once touched, and the demon's promise, have led her into peril. The book's new owner is hunting her, and her family's dark inheritance may hold the only key to her survival-or her destruction.

In a journey that will test her courage, her powers, and her fate, Martha must face the choices that will either reunite her family-or tear it apart forever.