The city is winchedalong tracks through a devastated land full of hostile tribes. Railsmust be freshly laid ahead of the city & carefully removed in itswake. Rivers & mountains present nearly insurmountable challenges tothe ingenuity of the city's engineers. But if the city does not move,it will fall farther & farther behind the optimum & into thecrushing gravitational field that has transformed life on Earth. Theonly alternative to progress is death.The secret directorate thatgoverns the city makes sure that its inhabitants know nothing of this.Raised in common in creches, nurtured on synthetic food, prevented aboveall from venturing outside the closed circuit of the city, they'recarefully sheltered from the dire necessities that have come to definehuman existence. Yet the city is in crisis. People are growing restive.The population is dwindling. The rulers know that, for all theirefforts, slowly but surely the city is slipping ever farther behind theoptimum.Helward Mann is a member of the city's elite. Better thananyone, he knows how tenuous is the city's continued existence. But theworld he's about to discover is infinitely stranger than the strangeworld he believes he knows so well.