About 20 years have passed since the relocation. The colonists are still settling into the Upper World lands that are new to them, but new and new problems keep arising. First, an unexpected threat emerged from the World they left behind. A small part of the people remaining there survived, managed to overcome the dangers of ptertopas (a disease caused by pterta), chose a new king—and now he demands that the settlers submit to his rule. Toller Marakain becomes the commander of the defense of the Upper World, and under his leadership, on the way toward the World, flying fortresses (wooden!) are built, which will block the path of the invaders’ air fleet. Second, one of the groups of settlers, having moved into convenient lands, faces mysterious problems. The inhabitants suffer nightmares—some of them seem to go mad, and some even disappear. Later, these plotlines will connect.