Earth's crust is breaking up. In the aftermath of a seismic shift, Maddie and her little brother Fin fend for themselves. Alone. They find a hidden people called the Mym, subjects of a government experiment that has spiraled out of control. Maddie learns the secretive beings could hold answers to why the planet is crumbling. But most importantly, she must protect Fin from this angry new world and, worse, the violent gangs who roam its smoking ruins.