Mara and her ship of refugees have escaped the sky city of New Mungo and are tracking the North Star in search of a home in the mountains of Greenland. But Mara's journey turns tragic when her ship plows through a floating city, and an orphaned Gypsea boy becomes inextricably linked to her fate. Meanwhile, in the drowned ruins of New Mungo, Fox begins his battle with the corrupt rulers of the New World in the hope of forging a safe haven for all survivors. As the revolution begins, Mara and Fox are farther apart than ever . . . but can their love survive this test?