The novel is set in the future, when Malthusian overpopulation on Earth has been averted by the invention of teleportation, called the "Ramsbotham jump," which is used to send Earth's excess population to colonize other planets. However, the costs of operating the device mean that the colonies are isolated from Earth until they can produce something to justify two-way trade. Because modern technology requires a supporting infrastructure, the colonists employ technology from the frontier era (such as horses instead of tractors).