FOR THOSE DISAPPOINTED by the crass, truncated film of The Golden Compass, it is a joy to be reunited with the authentic creativity of His Dark Materials through another book. When Lyra met Lee Scoresby, the daring American aeronaut, and won the loyalty of Iorek Byrnison, the armoured bear, they were old friends, but in this tale both are young. Once Upon a Time in the North is about how they meet, join forces and save each other from danger. As you might guess from the title - a nod to Sergio Leone's Once Upon a Time in the West - we have been given a kind of cowboy tale, powdered with magic.

Scoresby has just won his balloon in a poker game and barely knows how to fly it. He's looking for adventure, or employment, and what he and Hester, his hare daemon, find in the port of Novy Odense is both. An ambitious politician, Poliakov, is trying to stir up hatred between men and bears, and he sounds Lee out for a job. Charmed by his beautiful but brainless daughter, Lee is tempted until he spies that Poliakov already has someone working as an enforcer for him: McConville, flagged up as villainous by having a rattlesnake for a daemon. It's only a matter of time, once the men see each other, before they and their daemons fight - and, sure enough, the story has a terrific climax that boys will find particularly rewarding.

Lee and Hester's laconic, sceptical sense of honour will win all hearts. This parallel world, where souls are visible as animals or daemons, is one that consistently engages the reader's moral intelligence even as it re-uses elements from both fairytale and Philip Pullman's own imaginative stock in trade. Fans will recognise a sinister machinegun that Poliakov has up his sleeve as being very similar to the one that Sally Lockhart blows up in The Shadow of the North.

Instead of the Church, the pretext for bullying and greed is political ambition aided by greed and fear, and ultimately confounded by love and courage. But as Lee is a young man rather than a child, we are allowed to know, when he meets Poliakov's daughter, that “Her body had its own kind of intelligence, just as his did, and their bodies had a great deal to say to each other”. His self-restraint is most satisfactorily rewarded.

Unlike Tolkien, C.S. Lewis and J.K. Rowling, Pullman's imagination is not enhanced but diminished by cinematic special effects because he has already played so creatively with the nature of reality. Post-modernism has always been more appropriate to children's literature than to adults'; the teases here about the veracity of the story we have just read (is it part of Lyra's M Phil dissertation on the patterns of Arctic trade?) make the narrative reach out of its frame, even as we readers long to reach into it and find it all true.

At 104 pages long, Once Upon a Time in the North is both a compelling adventure and the kind of philosophical game familiar from the author's shorter novels (I Was A Rat!, Count Karlstein and Clockwork). There are bills of lading, extracts from Lee's half-destroyed book on The Elements of Aerial Navigation, a fallacious newspaper report and a board game at the back about getting your balloon as close to the Pole without being “sucked into a terrible and certain death in the Polar Maelstrom”. Compared with the epic Miltonic grandeur of His Dark Materials we get more of a Blake poem.

It is exuberant, intelligent fun, in a way that his previous novella, Lyra's Oxford, was not, and the exquisite engravings by John Lawrence and small size of the book make it a joy to look at, touch and hold. The cowboy tale is a form long overdue for renewal (as Stef Penney's The Tenderness of Wolves also showed us last year): a heroic restoration of justice must be crafted from seemingly simple actions. Once again, Pullman has created a work of art that is enchanting for a child but equally appealing to an adult.

Once Upon a Time in the North by Philip Pullman
David Fickling, £9.99; 104pp

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