While many novels end with a cataclysm, Doris Lessing’s latest takes the less usual step of opening with one. It is a sequel to Lessing’s 1999 novel, Mara and Dann, but, whereas the earlier book was concerned with the struggles of its young hero and heroine in a world which while derelict and strife-ridden still retained the vestiges of civilisation, the later one depicts a society that has almost completely broken down.

Once again the setting is Africa (or rather Ifrik) several millennia after a second Ice Age has reshaped the globe. Deserts have been flooded, cities submerged and seas dried out. Although contemporary commentators identify a potential threat to Europe in the mass emigration of sub-Saharan Africans fleeing north to escape