Asa and Rollo are orphans, the royal children of the Star Lands. Emperor Flood, the powerful court magician who has usurped the power of the king and queen, has caused the water to rise, turning the Star Lands into a series of hill islands, sunken towers, and deep, motionless bays. Flood commands the sky patrols, which watch the waterways from their huge black balloons. A loyal family friend, Egil Cripplehand, gives Asa and Rollo his enchanted ship, Northseeker, so that they can rescue their infant sister Una from their parents' killers. but first they must outrun the sky patrols, using their special gifts to outwit Emperor Flood's forces.
