The Children of Húrin, by JRR Tolkien

The Children of Húrin is packaged as a prequel to Lord of the Rings. It comes with lavish and lovely artwork by Alan Lee - artistic director of the films - and has its own trailer on the web. The action, however, takes place six and a half thousand years and one geological upheaval before Bilbo's eleventy-first birthday. It's a prequel in the sense that a book about neolithic traders of the Dorset coast is a prequel to Persuasion.

There are no Hobbits cosying up with tobacco pipes and songs here. The book has the elevated, chilly tone of The Silmarillion. Its opening paragraph is an obstacle course of genealogical tongue-twisters. The narrative - doomed hero, serious dragon, terrible twists of mocking fate - has strong affinities with the Cattle Raid of Cooley, or the Finnish national epic, the Kalevala.

It's not supposed to be entertaining. There is no chance, for instance, of being surprised by the hero's death when one of the chapters is called "The Death of Túrin". It is dry, mad, humourless, hard-going and completely brilliant. My ten-year-old read it in a day and a half and has not shut up about it since.

Tolkien is always dismissed as a conservative, but what's striking about this book is how modern it seems. Not only because it is part of a total multi-media experience (which is not his fault), but also because of the nature of Tolkien's project. Clearly he was a terrific storyteller, but that was not his purpose. He was trying to create a separate world and the stories are only there to provide evidence of it. The Children of Húrin is a fictional artefact, like the maps, the grammars, the drawings, not about that world but of it.

Tolkien is often paired with CS Lewis, but he disliked Narnia and worked hard to make sure that Middle Earth did not descend to allegory. Allegory makes fantasy dependent on real life. He wanted Middle Earth to seem separate and real. When he first started work on this story as a young man recovering from trench fever in Staffordshire, he was hoping to create a new British mythology that would replace wishy-washy Arthurianism.

This may seems bonkers now, but it wasn't that unusual at the time. The Kalevala was synthesised from oral sources in the late 19th century and played its part in the founding of Finland. Yeats's Vision and Graves's The White Goddess are both attempts to generate new mythologies from old. Try getting your ten-year-old to read those.

One of the things that distinguishes Lord of the Rings is Tolkien's ability to suggest other stories yet untold, places yet unvisited. He says Shelob's hide, for instance, was so hard it couldn't be pierced even by the swords "of Beren or Túrin" of old. Conan Doyle used to do this too, alluding to cases like the Giant Rat of Sumatra for which there were no available stories. The difference is that Tolkien kept filling in the gaps.

The stories of Beren and Túrin are described here in full. He worked more or less all of his life to create an entire culture for Middle Earth - fairy stories, songs, creation myths, the lot. A lot of commentators have questioned Christopher Tolkien's role in bringing these early tales to light, but it's brilliantly appropriate that the stories have to be excavated by an Oxford scholar as though they were ancient manuscripts.

And Tolkien would have liked the idea that there was no definitive version. He seemed to think less like a novelist and more like a demiurge, or like the designers of the massive computer game World of Warcraft, on which he has been a defining influence. Unlike most novelists - but again like a games designer - he hoped other people would join in his enterprise. "The cycles should be a majestic whole," he wrote to Milton Waldman, "and yet leave scope for other minds and hands, wielding paint and music and drama." And this has happened.

Tolkien is a phenomenon now, but he was already a phenomenon when I was growing up. The difference is that now his fame is focused on the films, whereas then it was more disparate. Games, comics, rock music from Led Zeppelin to T. Rex were all suffused with Tolkienesque imagery. The whole "Goth" thing comes down to dressing up as ringwraiths. Mark Barrowcliffe's book The Elfish Gene is an account of growing up physically in Coventry while mentally in Middle Earth. Of all artists, probably only Disney has managed to make his vision so ambient. It is as though he was writing not onto the page but directly into our folk memory.

Maybe it's more than elves and hobbits. Maybe ideas like the evil empire, and our current sense of a world in terminal decline, come also owe something to Middle Earth. It would be difficult to argue that his dreams of replacing our native mythology hasn't come true, at least in part.

Frank Cottrell Boyce's latest book is 'Framed' (Macmillan)

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