At the southern end of a large land mass called Ifrik, two children, Mara and Dann, are victims of a palace coup and forced to flee from their home and family in the middle of the night. They are brought up in a poor rural village, surviving the hardships of a life threatened as much by drought and wild animals as by the hostile Rock People, who hate them. They join the great human migration northward, away from the southern lands that are turning to dust.
Mara and Dann encounter all kinds of people, survive many dangers. They are captured and enslaved, but escape, to be captured again in a country permanently at war. Dann becomes a general. Mara finds herself a soldier in the opposing army. Again they escape, always travelling north. She finds herself in a brothel only to run away. He nurses her through the terrible water sickness. This brother and sister love each other, save each other's lives a hundred times travelling north - but what is North and what will they find there?
Doris Lessing has written a compelling, troubling, and entertaining novel, with Mara one of her most appealing heroines and Dann as brave a hero as you'll find in any old tale. The remarkable odyssey of a brother and sister living in the imagined future manages to tell us a great deal about the present we only dimly perceive and scarcely know how to value.