Meet Diana Prince, a woman with a chequered past. Believing it was the only way to save a friend, she once killed a man, only to find the government pursuing her for murder. Finally exonerated, she joined the Justice Department, hoping to put her pacifism and humanity to good use.

But her late mother's friends want to do her in, her employers mean her no good, a terrorist war looms - and there's the small matter of an attractive new partner to contend with as well.

So far, so blurb; and just the sort of thing you might expect from Jodi Picoult, the American author of a string of bestseller based with canny foresight around the most troublesome issues and headlines of the day. But if Diana Prince's story seems to lack the hard focus of Picoult's other works - such as Perfect Match, about child abuse in the Catholic Church, or Nineteen Minutes, about a school shooting - there's a good reason. Diana has other problems too. She's thousands of years old, comes from a race of all-female immortals and is in permanent danger of falling out of her costume. Oh, the hell with it; she's Wonder Woman.

Picoult's run on DC Comics' Wonder Woman title, published this month as Love and Murder (Titan, £16.99) is the most recent illustration of a growing trend in comics: the celebrity guest writer.

For some time, the two biggest imprints, Marvel and DC, have welcomed writers and directors from Hollywood to write story arcs for their long-running superhero sagas. Famous names who have turned to comics, with varying degrees of success include Joss Whedon, the creator of Buffy, Kevin Smith, the writer-director of Clerks and Richard Donner, the director of Lethal Weapon. But this year, it's the novelists coming aboard.

The size of the influx is startling. Stephen King, one of the world's bestselling authors, has recently overseen the first in a series of comic adaptations from his Dark Tower novels. Ian Rankin, having retired the bibulous Inspector Rebus from print, has turned his attention to John Constantine, the hard-bitten Chandlerian sorcerer of Vertigo's Hellblazer comics. Michael Chabon has published several issues of The Escapist , a superhero created by the fictional protagonists of his novel The Amazing Adventures of Kavalier and Clay, while his contemporary Jonathan Lethem is halfway through a run on Omega the Unknown, a timely resurrection for one of the most philosophically baffling superheroes.

What's the attraction? Comics-writing is a painstaking process, more akin to screenwriting than straight prose, and the exigencies of such a visual form may come as a shock to novel writers. Then there are the fans. Each character in the Marvel and DC universes has the kind of fantastically involved history - full of reinventions, resurrections and fanatically debated points of orthodoxy - that corresponds more with myth or religion than popular entertainment. They enjoy the kind of collaborative longevity that simply doesn't exist in fiction; a sort of long-running narrative stonemasonry. Each successive writer or artist pays necessary homage to the story's previous custodians.

For writers used to the self-directed labour of novel-writing, the almost journalistic rules of comics may be a surprise. Neil Gaiman, perhaps the closest thing the world of comics has to a rock star, has described writing his cult series Sandman as “having to do that weird Charles Dickens-y thing that nobody gets to do these days, except for people writing comics. Which is write a 2,000-page story in public, and writing it with no room for change”.

Rankin, whose Hellblazer graphic novel is published later this year, was approached by Vertigo Comics after they read in an interview that he was a comics fan - he cites Watchmen, Alan Moore's classic deconstruction of the superhero myth, as one of his favourite novels. He says that he “grabbed the chance to fulfil the childhood ambition of being a comic-book writer”, but reality has proved more testing. “I'm enjoying the process, but finding it hard to think in such visual terms. Most of what I do is write instructions to the artist as to character description, visual point of view, etc, for each frame - all of which gets in the way of actual storytelling.”

Picoult, another childhood fan, also found the transition surprising. “It was so much harder than I thought,” she says. “When I write a novel, I'm used to making up my characters and their backstory. I couldn't change Wonder Woman's history, and she's been around a long time. I did attempt to get her out of that bustier - any woman can tell you that you don't fight crime without straps - but no cigar. Overall, I felt enormous pressure - how to leave my fingerprint on the most iconic female comic book character, without ruining her?"”

Picoult's experience suggests, however, that one inspiration for the new wave may come from closer to home than many writers would admit. When DC pitched the idea to her, Picoult says: “I didn't have any time to do it, although it was awfully cool to be asked. I went downstairs to dinner and told my family about the e-mail, and my kids looked at me like I was insane.

“‘Mom,' my 14-year-old said, ‘you HAVE to write Wonder Woman!' So I juggled and managed to fit it in.”

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