The Trappers, hunter-gatherers who live beside a mammoth wall of ice, have none of the wonders their carefully hand-copied, ancient Warm Times books describe, like cars, guns, or plows. When bloodthirsty invaders slaughter most of the tribe, a small band of survivors heads south, led by a man few of them trust. Holding the remnants of her people together is their doctor, Catania Olsen, whose ugliness has left her unmarried but whose medical skill has earned her people's respect.

The Trappers' hazardous trek takes them from their familiar frozen northland, where summer lasts two chilly weeks, through a burgeoning forest where people still know how to make paper, to a warm, bustling gulf coast trade mart where man-beasts created by unnatural science tread the dirt streets.

Journeying into the warm lands will change Catania, mind, heart, and soul. She will gain and lose a love, see great wisdom and greater folly, and become a mother. Finally, she will have to choose between her people and her freedom.