After her surprise discovery of a mystical gift, fourteen-year-old Rose Wilson thinks her life is ruined. It turns out she comes from a long line of gifted women, and despite her protests, Rose's mom ships her off to her grandmother's house to spend the summer learning about her family's well-hidden secrets. To make matters worse, Rose is expected to carry out this tradition alongside her mousy, bookworm cousin, Megan. What a waste of a summer.

With some effort, Rose and Megan manage to find common ground and by the time they get home, they're working together to adjust to their new life. But everything is turned upside down again when their families are exposed by witch hunters who call themselves The Witches' Hammer. With killers on the loose, their tiny town isn't safe anymore. Rose's entire family is fragmented and forced to flee through a network of hiding places, dubbed The Witches' Underground Railroad.

As she journeys to the sea, Rose learns more and more about who she really is. The closer she gets to her destination, the more danger she encounters, until she is forced to make the ultimate decision: follow her family's edict of non-violence and become an orphan, or save her mom's life.