
Helward Mann is a member of the city's elite. The rulers know that, for all their efforts, slowly but surely the city is slipping ever farther behind the optimum. Raised in common in creches, nurtured on synthetic food, prevented above all from venturing outside the closed circuit of the city, they're carefully sheltered from the dire necessities that have come to define human existence.

The secret directorate that governs the city makes sure that its inhabitants know nothing of this. The only alternative to progress is death. But if the city does not move, it will fall farther and farther behind the optimum and into the crushing gravitational field that has transformed life on Earth.

Rivers and mountains present nearly insurmountable challenges to the ingenuity of the city's engineers.

Rails must be freshly laid ahead of the city and carefully removed in its wake. The city is winched along tracks through a devastated land full of hostile tribes.
