Sweeps period is an exciting time on The X Files. Though it wraps with a two-parter feeding into the intrigue surrounding the feature film which will open this summer, the month leads off with episodes written by science fiction and horror legends Stephen King and William Gibson.

Co-written with fellow science fiction author Tom Maddox, Gibson's segment - which airs this week - features "absolutely unspeakable and rather darkly funny cruelty," according to the writer.

The official press release describes "Kill Switch" as a story about an unlikely killer capable of the worst kinds of torture. Gibson refuses to elaborate much - "Chris Carter would come over and tear my legs off" - though he does agree gleefully with the synopsis. "When they say 'the worst kind of torture,' you have no idea!" he cackles. "There's some really cool, shocking stuff."

The writer does allow that this is the only X Files episode ever to have name-checked the Santa Fe Institute. "The Santa Fe Institute is the premier place in the world for the study of the science of artificial life," he adds mysteriously. "And that's as much as I can say."

Gibson, a multiple winner of Hugo and Nebula awards, was one of the creators of the cynical, high-tech brand of science fiction popular throughout the '80s and '90s. His novel Neuromancer received wide acclaim as the progenitor of cyberpunk, a school of science fiction concerned with the dehumanizing effects of technology on the immediate future of the human race, and how people might struggle to retain their humanity in an era of virtual reality. Though he wrote the screenplay for Johnny Mnemonic based on his own story, his experience with dramatic serials is rather limited.

"I'm kind of television-proof; there hasn't been anything much except The Simpsons that's got me tuning in on a regular basis," Gibson admits. He became a fan of The X Files when his daughter introduced him to the show two years ago, and discovered that it rang all sorts of bells. Because the series is shot in Vancouver, where the U.S.-born Gibson has taken up residence, he called some connections from the film industry and arranged for himself and his daughter to visit the set. "Then I kept bumping into Chris Carter every time I'd fly down to L.A., because he seemed to be on virtually every flight I was on - Canadian Airlines' business class Vancouver to LAX is all X Files people!"

Gibson was wary of writing for television because of his experience working on what he describes as "the somewhat ill-fated Johnny Mnemonic - I wrote the script we shot, I didn't write the script you saw!" He was pleasantly surprised when The X Files not only shot what he and Maddox wrote, but created the many expensive props he had described. "We thought, we'll write in three times as much stuff as they're likely to build, and then if they build a third of it, it'll be cool," he notes. In fact, they built them all. "They were very, very generous - there are a couple of very expensive, mind-blowing gadgets that are only briefly going to be onscreen, but they make all the difference. It looked to me like a real quality effort, the wholehearted, over-the-top effort they pitched into art direction."

Gibson adds that the themes of the episodes will be familiar to his readers. "What Tom and I both wanted to do was to write one of the stand-alone nightmares," as opposed to an episode which would fit into the conspiracy arc. "Without deliberately having tried to do this, we realized when we had finished that we had touched on pretty much everything that this particular school of science fiction I've been associated with tries to do. Probably the first and only cyberpunk X Files."

Gibson hopes there will be a passing nod to the mythology of the series, and says he's really anxious to see the feature film this summer, "to see how close they'll be able to come to pulling the giant backstory together." Nobody has been willing to tell him what will happen in the movie - information which is more closely guarded than President Clinton's dating habits - but "Kill Switch" was directed by Rob Bowman, who also directed the X Files movie, so there will be at least one connection between the episode and film.

As for his next project, Gibson is finishing a third and final novel in what has turned into a series, and then "would like to do something completely different, but I have no idea what that might be." He says his interests have been changing over his past couple of books, and he'd be willing to experiment a little more with writing for the screen.

"Every time I do screenwriting, I'm struck initially by how hard it is; it's alien to my nature, and the formal constraints are terrible and irrevocable. Yet by the time it gets to the point where I'm actually standing in a set that is somebody's realization of something that previously only existed behind my forehead, I'm so carried away by the magic of it that I want to do more. They build my gadgets!" he exclaims. "That's always a huge rush, aside from the astonishing speed of production in episodic television. You can turn something in and they have it in the can a month later. That keeps me coming back."

And since he hasn't seen his own X Files episode yet, Gibson anxiously awaits Sunday night. "You'll definitely get to see them do a few things that they haven't done previously," he promises.