Only guildsmen (all male) have access to the outside world and are oath-bound to keep what they know a secret in fact, most people do not even know the city moves.

The Militia provides protection, armed with crossbows, against tooks resentful of the city's hard bargaining and the taking of their women. The Barter Guild recruits labourers ('tooks') from the primitive, poverty-stricken nearby villages they pass, as well as women brought temporarily into the city to help combat the puzzling shortfall of female babies. Traction is responsible for moving the city, while the Bridge-Builders overcome terrain obstacles. The Track Guild tears up the track south of the city to re-lay in the north. His guild surveys the land ahead, choosing the best route. Upon reaching adulthood at the age of 'six hundred and fifty miles', Helward leaves the crèche in which he has been raised and becomes an apprentice Future Surveyor. The city's inhabitants live in the hope of rescue from their lost home world. The city, which Helward estimates is 1,500 feet (460 m) long and no more than 200 feet (61 m) high, is not on the planet Earth the sun is disc shaped, with two spikes extending above and below its center. Helward lives in a city called 'Earth', which is slowly being winched along at an average speed of 0.1 miles per day (0.16 km per day) on four railroad tracks northward toward an ever-moving, mysterious 'optimum'. The first, third and fifth sections are narrated in the first person by the protagonist, Helward Mann the second follows Helward, but is written in the third person while the prologue and fourth part center on Elizabeth Khan, also from the third person perspective. The book consists of a prologue and five parts.

A crisis ensues as its population decreases, the people grow unruly, and an obstacle looms ahead. Many people are unaware that the city is even moving. The city's engineers lay track ahead of the city, reusing old track the city has crossed over. In the novel, an entire city and its residents travel slowly across a supposedly alien planet on railway tracks (it is left unclear to the reader whether it truly is not planet Earth). In 2010, the novel was included in the SF Masterworks collection. The novel's basic premise was first used in the short story 'The Inverted World' included in New Writings in SF 22 (1973), which had different characters and plot. Inverted World ( The Inverted World in some editions) is a 1974 science fiction novel by British writer Christopher Priest.

The inverted world christopher priest