I didn't think I was going to like this novel, being unwilling to surrender to a parable about the travails of a brother and sister in a far country in the very distant future. But Mara and Dann had me by the throat immediately. Whenever I had to put the book down I fretted about the danger in which I had left the characters, until I could get back and let their story move along again.
We are in Africa, now known as Ifrik. The northern hemisphere has succumbed to a new Ice Age, and is uninhabitable. No one is sure how many thousands of years ago it was that the civilisation of Europe and North America was annihilated by ice, since concepts of number have