The day Kit Pen receives a Mechanical Equus for her birthday is a day that changes her life forever. She begins dreaming of a creature everyone's told her no longer exists: the horse. A cry from a phantom animal draws her from the edges of the grazing pastures of her father's ranch to the unknown beyond home. She follows the mysterious cry to the woods, where she encounters a rebel camp and a ghost whose name means "freedom." There, her eyes are slowly opened to a world much darker than the one she is accustomed to, a world that is inextricably intertwined with her own.