By the time their boat reaches Peru, the only ones that have recovered enough to continue the expedition are the youngest in the group and the lowest in hierarchy — Donald and his nephews.

The father had found them on the body of an American explorer who had emerged from a neighboring valley, which is covered in perpetual mist.

They speak with an old American Southern accent taught to them by their previous visitor, the dead man, Professor Rhutt Betlah (a wordplay on Rhett Butler)[1] from Birmingham, Alabama, who had discovered their valley during the late 19th century.

The only way to get out of the valley and avoid capital punishment is for Huey, Dewey, and Louie to produce square bubbles.

They give the Ducks a compass that the professor had left in Plain Awful, having been placed in a museum as a piece of art and, in return, they teach them square dancing.

It's only when they return to Duckburg, that they realize the entire expedition was a failure: both of the chickens are male and naturally can't reproduce.

A mythical creature or legendary artifact that leads to an expedition, the long search for information, often seeming futile, an isolated civilization hidden from the outside world thanks to its natural environment, the Ducks bringing new ideas with them but sometimes faced as threats, and the characters ending up defeated or empty-handed are all such themes.

Although he finds them superior to capitalist modernity, Barks rejects a romantic primitivism that elevates preindustrial cultures to the status of utopias.

The Plain Awful's square egg is also featured in Don Rosa's The Buckaroo of the Badlands, part three of his famous The Life and Times of Scrooge McDuck.