McKie learns from a friendly Caleban that they have helped the Gowachin with an experiment that has lasted several generations: they have "accidentally" mistransported various humans and Gowachins to a planet named Dosadi. A "God Wall" keeps them in and everyone else out. Because the planet has poisons everywhere, the millions of inhabitants live in one valley. Their artificial society, already under immense pressure, will explode unless something changes.
With an assumed identity, McKie teleports to Dosadi. The ruler, a Gowachim named Broey, has concentrated his forces to defend against an expected uprising. McKie tracks down the "rebel" leader and finds Keila Jedrik, a human woman and civil servant who has orchestrated civil unrest and rebellion. As in several other Herbert works, a principal character undergoes an evolutionary gestalt.
Contains examples of:
- The End of the World as We Know It: Dosadi might self-destruct or it might take over the galaxy. Other, "minor" risks include the whole ConSentiency becoming a nastier place (if the experiment succeeds) or turning into complete madhouse as a result of leak.
- The Federation: The ConSentiency, consisting of a wide variety of alien cultures and societies.
- Frog Men: The Gowachins, aliens resembling large humanoid frogs. They can breathe both air and water and are highly amphibious — their homes typically contain a number of flooded rooms and tunnels — and go through a tadpole phase after birth.
- Psychic Link: McKie and Jedrik as a side effect of Body Swap.
- Read the Fine Print: One would think that the Gowachin, while preparing a contract with entities having utterly alien minds, always sticking to the letter of their obligations as they understand them, and manipulating stellar amounts of energy apparently at will, would clarify each point as much as humanly (and inhumanly) possible. But no one did a good job in this area. A lot of people ended up with quite unexpected results, and the whole ConSentiency barely survived.
- Showing Off the New Body: After learning they can switch bodies at will with each other, McKie and Jedrik have some interesting sex.
- Take That!: Herbert has a couple here, aimed at his more famous work, Dune. McKie is worried about being seen as some sort of Messiah; a native Dosadi replies that it would be utterly stupid for them to worship or follow him, he's just an outsider...
- The Wall Around the World: The God Wall that surrounds Dosadi and prevents its inhabitants from leaving it or visitors from entering it.
- Training from Hell: Every living person on Dosadi is going through this just by living.
- Tough Love: Pretty much every parent on Dosadi (including Jedrik's) lives (or lived) this trope by necessity.