The novels are set in a postapocalyptic world ravaged by a nuclear conflict known as the Sixty Minute War, which caused the loss of much technological and scientific knowledge, as well as the greater part of the world's human population. Following the war, the world suffered a period of immense geological upheaval, in which volcanoes, earthquakes and tsunamis harassed surviving human settlements.

To survive these phenomena, Traction Cities were invented: enormous, mobile cities which could escape dangerous areas. Naturally these huge cities required vast amounts of fuel, and quickly began to strip the world of its natural resources. After some time, as resources dwindled, a system called Municipal Darwinism was devised, in which cities began to "eat" smaller cities and towns, by chasing them, dragging them inside and melting them down for fuel and materials.

Those opposed to the concept of Traction Cities and Municipal Darwinism formed the Anti-Traction League, which sought to restore the Earth to its former ecology. The league holds sway in Asia and much of Africa.
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