CANNES, France (AP) - Indiana Jones doesn't give up his secrets lightly, and neither does the man pulling his strings.

Director Steven Spielberg has tried to keep chapter four of the archaeologist's big-screen adventures, "Indiana Jones and the Kingdom of the Crystal Skull," under wraps as tight as an ancient mummy's.

The stealth approach has whipped up a frenzy of expectation - and doubts about the movie's quality - as he prepares to unveil it in front of the world's toughest audience, critics at the Cannes Film Festival. The film premieres here Sunday, just four days before it opens in theaters worldwide.

In an era of Internet spoilers, fan blogging and online video diaries where filmmakers show off their tricks, Indy returns with the old-fashioned covertness Spielberg always has favored.

"He is the only one in the world who keeps his cards face down on the table until the 11th hour, 59th minute, 59th second, and nothing deters him from doing that," said Jeffrey Katzenberg, Spielberg's partner at DreamWorks.

Revealing their cards at Cannes, with its notoriously snooty press corps, is a critical risk for Spielberg, executive producer George Lucas and star Harrison Ford.

Hollywood trade paper Variety quipped that Indiana Jones was entering the "Kingdom of the Critical Knives," and reporters have joked that Cannes might prove a new Temple of Doom for Indy.

Two years ago, the first press screening of "The Da Vinci Code" drew open laughter from Cannes critics, whose harsh reviews spoiled the film's premiere a day later and set the stage for a worldwide critical drubbing.

Of course, "The Da Vinci Code" went on to gross $758 million globally. As the first movie in 19 years for one of cinema's biggest adventure series, "Crystal Skull" is virtually assured of blockbuster results, too.

Possibly to shield "Crystal Skull" from a similar critical backlash, Spielberg, Lucas and distributor Paramount weren't letting critics see the movie until hours before its Cannes premiere.

In an unusual move, the few cast and crew interviews at Cannes were scheduled Saturday, before reporters had even seen the film. The movie's profile is so high, the filmmakers figure it doesn't need the usual publicity.

Spielberg has been hush-hush from the start. Co-star Karen Allen, reprising her "Raiders of the Lost Ark" role as Indy's old flame Marion Ravenwood, said Spielberg initially wanted to keep it a secret that she was even in "Crystal Skull."

"Even after the film was announced, people would call me. `Oh, it's too bad you're not going to be in the film,'" Allen said. "I had to go along with it and say, `Yeah, it's a shame.' When it was finally announced I was in it, it was a huge relief. I was having to make up stories for why I wasn't in it, and I was finding it excruciating to have to do that."

In its earliest incarnation, Lucas proposed an all-out alien flick called "Indiana Jones and the Saucer Men From Mars." Spielberg and Ford didn't like that idea, and it took more than a decade of wrangling to come up with a story all three could live with.

A trailer showing a crate marked "Roswell, New Mexico, 1947" - a mecca for UFO buffs - hints that the movie retains traces of its extraterrestrial origins. Remarks by Lucas that the new film took its cue from 1950s sci-fi tales backs up that notion.

"The B-movies of the '50s were crazy science-fiction films, `It Came From Outer Space' and `Them!' and I said, `Well, gee, I could use that as the basis of the genre that I was using as my reference,'" Lucas said.

From the trailers and studio press materials, the basic story line is out there - Indy and Soviet agents led by Cate Blanchett pursue a crystal skull that can bestow fantastic power on those returning it to a city of solid gold in the Amazon from where it was stolen.

Secrets remain, such as how Indy and Marion are reunited and whether co-star Shia LaBeouf is playing the love child of their "Raiders" romance.

Spielberg was incensed last year when an extra leaked plot details, and the filmmakers have scrambled to maintain the mystery.

"It's been insane," said Frank Marshall, producer on the "Indiana Jones" movies. "I've spent a great deal of time on this movie just trying to keep things off the Internet. That's totally new for us. There seems to be some kind of sport out there now to see who can put up a spoiler, which is not fair to the audience. We really tried to keep the lid on the story just for the audience's sake."

Accustomed to fan gripes from his "Star Wars" prequels, Lucas has downplayed expectations for "Crystal Skull," saying audiences will be disappointed if they're anticipating a cinematic Second Coming.

Such remarks could just be part of Lucas and Spielberg's strategy to keep fans guessing.

"There's a little P.T. Barnum in both of them. They know how to get you interested," said "Crystal Skull" screenwriter David Koepp. "There's nothing more interesting than saying, `You can't see what's under here. I'd love to show you what's behind there, but I just can't.'"

Even a short behind-the-scenes segment on the official "Indiana Jones" Web site doesn't show much from behind the scenes. It focuses mainly on Spielberg in generic filmmaking mode, revealing virtually nothing about the action, ending with a close-up of Spielberg finishing a shot.

"And cut," Spielberg says. "Very nice."

The tough crowd at Cannes will have something to say about that Sunday.

On the Net:

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