It's a mystery worthy of Fox Mulder's scrutiny: Why make a theatrical motion picture of that iconic '90s TV series "The X-Files" six years after the last original episode aired? Nobody's doing "Seinfeld: The Movie," "Friends Forever" or "Walker, Texas Ranger, Rides Again."

But "The X-Files" is science fiction, and as we know from Trekkies or Trekkers or whatever the FC (fannishly correct) term is these days, sci-fi love never dies. And this past February at the WonderCon convention in San Francisco, those true believers known as X-Philes were sending X's - as in kisses - to the movie's producers and stars on a panel promoting "The X-Files: I Want to Believe," opening Friday.

From the screams and squeals captured in a featurette on the new DVD episode-set "The X-Files: Revelations," you'd think Elvis was in the building.

"We wanted this movie to work for and be loved by fans of the show," says former series executive producer Frank Spotnitz, who wrote and produced the movie with "X-Files" creator Chris Carter. "But if it only works for them," he frets, "it's not a success."

It does make your mind boldly go to "Star Trek: The Motion Picture" (1979), released 10 years after the TV series ended and five years after the Saturday-morning animated spinoff. Like that first "Star Trek" movie, the 1998 film "The X-Files" got a middling reception at best. And if this second film turns things around like the critical and commercial hit "Star Trek II: The Wrath of Khan," stars David Duchovny and Gillian Anderson might just wind up this generation's William Shatner and Leonard Nimoy (or, perhaps, Nichelle Nichols).

Pondering the future

The movie takes place six years after the events of the series finale, which, bizarrely, echoed the final ""Seinfeld": a trial, with recurring characters from the series showing up to testify and yada yada yada. In the end, FBI agent Fox Mulder (Duchovny) - investigator of aliens, monsters and other things that go bump on the screen - escaped his kangaroo court with the help of, among others, his FBI superior, Walter

Skinner (Mitch Pileggi, who appears in the film). Mulder goes on the run with his no-longer-skeptical partner, Dana Scully (Anderson). We last see them together in a hotel room, pondering the future and what to believe in.

Unlike "Lost," which has a similarly supernatural back-story mythos, the final "X-Files" seasons were all dangling and muddled loose ends. If the producers ever had a planned-ahead revelation, answer or overall point, it had gotten, well, lost.

"The show clearly didn't unfold the way anybody anticipated," Spotnitz says. "It doesn't have the great circularity of a novel. It changed gears in ways we hadn't anticipated. I understand why a lot of fans weren't as emotionally invested in those last two years as in the rest."

The harsh realm of reality didn't help. "I have come to believe the show ended when it did because of the post-9/11 mood of the country," Spotnitz says. "I remember the Sunday New York Times Magazine a couple weeks after 9/11 having a list of things that were 'in' and 'out,' and 'The X-Files,' it said, was out. And I thought, 'Why would we be out?' And when we came back on TV after that, the audience just didn't show up for season nine. People felt it was an antigovernment show, and out of step with the mood of the country."

Now? "My sense is we're now in a 'post-post-9/11' frame of mind."

Calling in a specialist

In the new film, according to the movie's trailer and the novelization by mystery writer Max Allan Collins, rural women are being abducted, grotesque human remains appear and a disgraced priest Joseph Crissman (Billy Connolly) has visions that lead police to a place of bizarre medical experiments.

The FBI gets involved, but the X-Files office has been closed. So ASAC (Assistant Special Agent in Charge) Dakota Whitney (Amanda Peet) calls in a specialist - former agent Mulder. Naturally, that also means former agent Dr. Dana Scully. We don't know what "Battlestar Galactica's" Callum Keith Rennie is doing there, but rapper Alvin "Xzibit" Joiner plays FBI agent Mosley Drummy.

However, "Robert Patrick and Annabeth Gish are not in this," Spotnitz reveals, speaking of the latter seasons' stars. That's something of a scoop - Carter has said in interviews that the fate of Scully's infant, William, will "not go unconsidered," but otherwise, they've been treating this TV-show movie with more national-security measures than the Cigarette-Smoking Man, the series' devilish antagonist who apparently died at the business end of a helicopter missile in the finale.

Between that final episode and now, Spotnitz reflects, he and Carter "had changed, and realized the characters would have changed as well. You get older, and what matters changes, and your perspective on life, I like to think, deepens."

Mulder and Scully now "struck me as more poignant than I'd appreciated before - how much they'd been through; how much they'd lost."

Whether audiences will be similarly affected, who knows?

You say you want a revelation?

I want to believe ... that the new two-disc DVD set "The X-Files: Revelations" really is an "essential guide to 'The X-Files' movie" opening Friday and "eight critical episodes," as the disc-jacket claims. Then I realize, didn't the filmmakers go out of their way to say they made a movie you could appreciate without having seen the TV show?

Spooky. This must be essential for that "X-Files" movie from another dimension, where you need to do your homework first.

What "Revelations" is - and it's not a bad thing, at that - is a collection of some of the stars' and filmmakers' favorite episodes, such as actress Gillian Anderson's ("Bad Blood") and creator Chris Carter's ("Memento Mori"). Each has an introduction by Carter and his main executive producer, Frank Spotnitz, and there's only one of those pesky "mythos" episodes about the overarching alien-invasion conspiracy.

There's even an actual revelation: Bob Newhart had been the producers' first choice for the title role in "Clyde Bruckman's Final Repose," for which Peter Boyle won a well-deserved Emmy Award.

Rounding it out are trailers for the series DVDs and the movie, and a 27-minute fan Q&A with the film's stars and producers. And a couple of early softball questions aside, the astute fans could actually teach Larry King and Barbara Walters a thing or two.