AN EXPLOSION WAKES Asa and Rollo in the middle of the night. It’s their enemy, the evil emperor Flood, destroying the homes of innocent people in his search for the two royal children! In order to protect the people around them, Asa and Rollo know they must leave and search out the man they have been avoiding all along. They sail the invisible ship Northseeker to Flood’s stronghold, Castle Crag. If they are lucky, they will find their mother and father in the castle’s dungeons. But one thing they know for sure—it’s time for a final showdown with Flood!