Nation, by Terry Pratchett

The funny side of truth on an island of lost souls

Terry Pratchett is an indisputable one-off. Aged 15 when his first story was published, he has gone on to write many more completely individual graphic novels, plays, children's books and science-fiction stories. There are also over 30 titles in his extraordinary Discworld series. As he draws from Ancient Egyptian culture, opera, Shakespeare, the Marx brothers and legions of other sources, nothing he writes is ever predictable – except that it will always be gloriously readable. Now, aged 60 but faced by a diagnosis of early-onset Alzheimer's, he presents his all-age fans with one of his finest books yet.

Set on a tiny island in the Pacific threatened by pirates as well as by its inheritance of accumulated ignorance and prejudice, Nation shows how individuals with intellectual courage can still help bring about a just society capable of defeating its worst enemies. Like Philip Pullman, Pratchett has a liking for parallel worlds. In this novel Daphne, a conventionally reared adolescent in a half-recognisable period of British history, is wrecked following a tsunami. She meets teenage Mau, the only local survivor. Together they learn to communicate, each cautiously giving up their received ideas. They are then faced with crowds of refugees making their way to the island, in flight from a group of marauding cannibals.

But Mau's greatest task is to cease believing in his tribe's fiercely patriarchal gods, whose gloomy injunctions make themselves heard in his subconscious. Daphne also has to dismiss everything her poisonous British grandmother has taught her about class or race. Slowly, the two work out a common language and a system of beliefs.

The idea of starting out afresh on a tiny island has brought out the best in fiction writers from Defoe to William Golding. Children relish these stories, but in this novel Pratchett is writing for everyone. Mau's Dawkins-type monologues as he questions all his supernatural beliefs go on a bit at times, but also point the way to Pratchett's central belief in the power of science and reason to liberate – if left in the right hands. True to form, Mau's island ends up incorporated by the Royal Society as a haven for visiting scholars.

Odd anthropological insights – sometimes backed up by jaunty footnotes – combine with fantasy as Pratchett introduces tree-climbing octopuses and beer that has to be spat in to make it potable. There are plenty of jokes. Aware that local gossip is trying to pair her off with Mau, Daphne thinks "It was like being in a Jane Austen novel, but one with far less clothing".

Devoted readers seldom get the chance to celebrate their favourite authors en masse. But if Pratchett's many fans ever got the chance, they could certainly fill the largest football stadium in the land. If they also started chanting "There's only one Terry Pratchett!", this would be no more than a truth universally acknowledged.