Several years earlier, Nellie and her mother fled the Interior and its hated security police for the Outbacks, a loose-knit resistance of small cities, towns and rural areas. Since then, her mother has disappeared and 12-year-old Nellie is on her own, scrounging a living where she can find it. When loneliness opens her mind to flux, the ability to alter her vibratory state in the molecular field, she learns to travel to other levels of reality. When a prank by the Skulls, an unruly gang of boys, reveals several large scars on her scalp, Nellie is forced to confront the terrifying truth that her vague memories of experiments that took place while she lived in the Interior are real. Befriended by 14-year-old Deller, leader of the Skulls, Nellie learns of the disappearance of his younger brother Fen. Using her ability to travel the levels, she eventually finds Fen trapped in an experimental laboratory deep in another reality. Although Nellie is unable to free him, her discovery precipitates a series of events that lead her and Deller back to the Interior, and straight into the memories she has been trying so hard to forget.