Charlie has been watching his father work on his latest invention, a large-scale version of the Worm Tub prototype. Construction attracts scores of visitors from the surrounding area. Locals are at first frightened of and intimidated by “Fat Boy.” Allie instructs Charlie to enter the chamber at the bottom and climb up through Fat Boy and out the top hatch. Inside the chamber, contorting himself through the convoluted network of jointed pipes and coils, Charlie suddenly has the impression that he is inside his father’s brain. He likens the complexity to something he cannot fathom, something beyond his comprehension.

Allie leaves Jeronimo to acquire the chemical compounds required to operate Fat Boy, and Charlie reflects on how quiet and peaceful the settlement has become since his departure. In his absence, Mother seeks out the Zambus and immerses herself in the opportunity to learn homemaking techniques from them. With the freedom to explore, the Fox and Maywit children happen upon a freshwater pool surrounded by edible plants, populated by animals, and tucked away unto itself. In this secret haven, which the children name The Acre, they set up camp and construct a society all their own, replicating the institutions and organizations which are forbidden in Jeronimo.