Too many children’s books are garishly produced with a cheap, throwaway look. Patricia Wrightson’s Shadows of Time will appeal to the aesthetically sophisticated child - it’s a very beautiful object, slender, sepia and bronze.

The language Wrightson employs to tell her story is similarly exquisite, plain and powerful - a joy to read aloud for its sheer poetry. Here she describes the sound of the ocean heard for the first time: “It spoke like God: one single word too loud and simple to be heard.” The plainness of the language lends it a timeless quality which accords well with the subject matter.

The story is set in Australia, the year of its beginning, 1799. Two children, an escaped kitchen maid from a convict settlement, and a half-white, half-native boy (nameless because Aboriginal names must never be spoken), meet and join forces. For the remainder of the novel the children wander Australia having a series of realistic and mystical adventures as time rolls past them - it only gradually becomes apparent that they are living outside the usual laws of time. Over the following two centuries they remain children, becoming legendary among native Australians as a pair of blue-eyed devils that haunt the land.

By the close of the book, Australia is the country we recognise today. Seen illuminatingly from the point of view of outsiders, it seems dangerous as well as exciting. Throughout the children’s quest to locate the spirit of the boy’s ancestor, Sarah Jane experiences periods of home- (or humanity-) sickness. She decides: “I want to be real, not hiding away like devils.” But the people themselves have changed so much she is intimidated and unable to relate to them: “They spoke loudly in short, sharp phrases, using few words and packing extra meanings into them . . . They wore strong, hard colours and an odd mix-up of clothes, and their hair was long, or short, glued together in strips or sometimes shaved off. It was hard to tell males from females.”

The plot straddles the boundary between the natural and the supernatural - both children have elemental abilities. Sarah Jane can sense the presence of water; the boy has absorbed the spirit of fire. They live by senses other than the usually acknowledged five: “We knew with another ear.”

This magical element is, in narrative terms, a flaw. For although there are exciting passages, the children’s ability to survive any threat, to live outside the ravages of time itself, means we cannot fear for them. Even when they are swallowed, along with their guardian spirit, by a giant snake, they are disgorged unscathed. The eventual result of this uncertainty about what constitutes danger is a lack of narrative tension and in the second half the pace occasionally tends towards the monotonous.

This story, though, will make children think. It will encourage exploration of the concepts of civilisation and progress and of cultures and realities other than their own. Teachers will like it - and it is a book that will enchant the more imaginative and reflective child.