In the future,
Malthusian overpopulation on Earth has been averted by the invention of
teleportation, called the
"Ramsbotham jump", which enables the excess population to colonize other planets. However, the cost of the technology means that colonies remain isolated from Earth until they can produce something to justify two-way trade. Because modern technology requires a supporting infrastructure, the colonists employ easily maintained technology similar to that of 19th century pioneers (such as
Conestoga wagons and horses rather than tractors). Rod Walker, a high-school student, dreams of becoming a professional colonist. The final test of his Advanced Survival class involves staying alive on an unfamiliar planet for between two and ten days. Students may team up and equip themselves with whatever gear they can carry, but they are otherwise completely on their own. They are told only that the challenges are neither insurmountable nor unreasonable. On test day, students walk through a Ramsbotham portal and find themselves alone on a strange planet, but reasonably close to the designated pickup point. Rod, acting on his older sister's advice, takes hunting knives and basic survival gear, avoiding high-tech weapons that might make him overconfident. The last advice that the students receive is to "watch out for stobor." On the second day, a thief ambushes Rod and knocks him unconscious. He wakes up to find all that he has left is a spare knife hidden under a bandage. In his desperate concentration on survival, he loses track of time. Eventually, he teams up with Jacqueline "Jack" Daudet, a student from another class whom he initially mistakes for a male. When she tells him that more than ten days have elapsed without contact, he realizes that something has gone wrong and they are stranded. Rod and Jack start recruiting other survivors to build a settlement for long-term survival, and Rod becomes the
de facto leader of a community that eventually grows to around 75 people. Disagreements reveal the need to elect a government for the new town. Rod has no taste for politics or administration and is happy to have Grant Cowper, an older college student and born politician, elected as mayor. Grant proves to be much better at talking than getting things done. Despite disagreeing with many of Grant's policies, Rod supports him. Grant ignores Rod's warning that they are living in a dangerously hard-to-defend location and that they should move to a cave system that he has found. When an indigenous species that the humans had regarded as harmless suddenly changes its behavior and stampedes through the camp, the settlement is devastated and Grant is killed. The citizens elect Rod as their new mayor. Heinlein tracks the social development of the frontier community of educated young Westerners deprived of technology, followed by their society's abrupt dissolution when Earth reestablishes contact. After nearly two years of isolation, the
culture shock experienced by the survivors highlights for them and the reader the pain and uncertainty of becoming an adult by reversing the process abruptly. Each of the students returns from being a self-responsible member of an autonomous community to being regarded as a youth. All of the students go back to Earth willingly enough except for Rod, who has great difficulty reverting from the status of head of a small but sovereign state to a teenager whom the adult rescuers casually brush aside. However, his teacher (and now brother-in-law) and his sister persuade him to change his mind. His teacher also informs Rod that his warning against "stobor" was just a way of personalizing the dangers of an unknown planet to instill fear and caution in the students, as all students receive the same warning, regardless of the planet they are sent to for the final exam. Years later, Rod accomplishes his heart's desire: leading a formal colonization party to another planet. ==Themes==