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."

The movie, which opens Friday, July 25 takes place six years after the events of the series finale in which FBI agent Fox Mulder (David 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 (Gillian Anderson). We last see them together in a hotel room, pondering the future and what to believe in.

"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."

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."

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.

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?