Anderson tells of Nehru II, a planet with a harsh environment, settled by humans, which has fallen out of contact with Earth and does not respond to any messages.
He subsequently meets a number of sub-human savages, startling but largely harmless, and two relatively normal humans, Stanley A. Menderstone and Alice.
Earth had purposefully not allowed sophisticated equipment be sent with the original settlers of Nehru II in an attempt to make them dependent so they could not possibly rebel in the future, but as a result the settlers found themselves in conditions not unlike prehistoric Earth, having to contend with the environment, shape simple tools, and make fire from basic materials.
On the way, he hallucinates other animals and events, supposed to be a racial memory of prehistoric times, and finds himself unable to handle artificial objects, repulsed by their alienness.
Despite his early statements to the contrary, he eventually abandons his clothes and weapons and runs to join the blissful Neanderthals in the forest.
Euler and Dominant demand to know the meaning of this story, which Anderson is unable to give, insisting that it was nothing more than a bit of fancy.
When pressed, Anderson relents that it might represent the inability of a society to truly move onto a higher, more advanced mode of life when the presence of the primitive still holds it back.