The City of Ember. By Jeanne DuPrau. Doubleday pound;10.99

Eragon. By Christopher Paolini. Doubleday pound;12.99.

The Prophecy of the Gems. By Flavia Bujor. Collins Children’s Books pound;10.99

A defining characteristic of fantasy is that the nomenclature should make interesting noises but not actually mean anything. Jeanne DuPrau’s debut novel, The City of Ember, is not fantasy but plain old science fiction, and the name is important. My dictionary defines ember as “live coal or wood in dying fireI almost extinct residue of activity”. The city is exactly that, a community tottering into decline and chaos. All light is artificial and no one knows what lies beyond the city’s boundaries. Surrounded by total darkness and powered by a single gigantic and disintegrating generator, it is plunged into total darkness at night. Then the lights start to go off during the “day”, and the hitherto apparently inexhaustible supplies of food and consumer goods begin to run out.

Two 12-year-old school-leavers, by virtue of their first jobs as messenger and maintenance man, gradually and unintentionally unearth the facts and find their way out. Only then do they discover the truth. The reader knows from the start that Ember was designed to have a finite life; but why? Anyone who lived through the Cold War will soon work out what is going on, but children ought to be mystified and intrigued. DuPrau, a Californian who presumably knows all about blackouts, is a most engaging writer: direct, succinct, delivering lively characters and genuine suspense, sustaining the mystery but generous with her clues.

The eponymous hero of Eragon hatches a dragon’s egg and, accompanied by a bearded sage, embarks on an predictable quest to combat the forces of evil as personified by people with daft names speaking in tongues (glossary appended). Perfectly ordinary words are rendered arcane by the scattering of random diaereses and greengrocers’ apostrophes. Christopher Paolini began this book when he was 15. He is now 19 and may be unstoppable. The first of a trilogy, it evokes the sceptre of the hapless author in Michael Chabon’s Wonder Boys who keeps writing because he cannot stop, grimly sitting down to page 2,611 of single-space typing. Happily, his editor loses hold of the manuscript in a high wind.

Flavia Bujor, 14-year-old French author of The Prophecy of the Gems, began it when she was 12. Possibly the editor and the translator are also 14. The story, a sort of Barbie-style quest tale with glittery bits, shows a precocious stamina, but Bujor does not write well. Her reach is way beyond her grasp, which is as it should be, but her way with cliches does nothing to develop her ambitions.

Fledging writers necessarily recycle their own reading in their apprentice pieces; this is the way we all learn how to do it. But these experiments ought to be carried out in decent privacy, not marketed as the masterworks of infant prodigies. It appears that considerable effort and expense have gone into promoting these last two books.

An element of protective mimicry has long been evident in publishing; if something succeeds then anything that resembles it is likely to succeed. A quick survey of bookshops confirms this - Eragon and The Prophecy of the Gems are facing out on the shelves and in tempting heaps on tables, not because they are exceptional but because they are a safe sales bet.

The City of Ember is on display in one local store; in another, a request unearths the single copy in stock. It shares a publisher with Eragon but has not shared its level of publicity. Everything about DuPrau’s book is attractive, from the handsome and intelligent cover to the narrative voice, ideal for reading aloud. One can only infer that these are insufficient grounds for bringing it to the attention of prospective readers.