It is not a sequel, nor a spinoff. It is wholly original with no big stars, meaning it has to try harder to draw an audience. Sneak previews and Twitter are part of the strategy.

The new retro sci-fi film "Super 8" heads into the summer movie season with two of Hollywood's biggest marquee names above its mysterious title: writer-director J.J. Abrams and producer Steven Spielberg. Yet in an era of sequels, spinoffs, book adaptations and television show remakes, the movie stands as an anomaly: It's a wholly original project with no A-list actors in starring roles.

The nature of "Super 8" — and Abrams' wish to preserve its mystique — has forced Paramount Pictures to handle the release with the kind of special care typically bestowed on an art-house endeavor. The studio announced via Twitter Wednesday morning that the film, which will open nationally on Friday, will premiere in about 325 sneak previews Thursday.

The hope, executives say, is that word of mouth will help bolster interest in the story of a group of friends who find themselves in danger after witnessing a massive train derailment.

Heart isn't typically what sells summer tent-pole projects, meaning that "Super 8" may offer the season's best test of the promise — and peril — of word of mouth."The strength of 'Super 8,'" said Rob Moore, Paramount's vice chairman, "is the movie's heart."

Audience tracking surveys show that though older moviegoers, particularly men, are interested in seeing the picture, younger ticket buyers — historically, the drivers of summer smashes — have been slow so far to warm to the film. In other words, people who remember 1979 (and the Spielberg films that inform this new movie) are more likely to want to see "Super 8."

The Spielberg touches are easy to find in the film as it follows a band of adolescents growing up in a small Ohio town in 1979.Obsessed with making their own zombie movie (their camera uses Super 8 film), the kids witness a secret military train's crash, soon followed by mysterious disappearances. Dogs run away, people vanish and large electrical components go missing.

Despite the elaborate derailment sequence and some special effects, Paramount said "Super 8" cost just $50 million (although one person close to the production not authorized to speak for the studio said it was closer to $55 million) — less than a third of the budget of last weekend's "X-Men: First Class." That means "Super 8" does not have to land a knockout punch in theaters this weekend to be on track to be profitable.

Indeed, given that the latest "X-Men" movie is sparking moderately steady traffic through the middle of the week, it's altogether possible that "Super 8" could trail the comic-book prequel for first place on the box-office charts come Sunday.

There's some evidence this week that moviegoer enthusiasm has ticked up, giving the studio hope that buzz is building in the last few days before release. But still, people who have analyzed the data say "Super 8" likely will take in a little less than $30 million on its first weekend — a solid start given the film's budget but a relative shrimp in the summer tent-pole season. (Paramount insiders point out that the 2009 science fiction film "District 9" began its theatrical run with a $37 million weekend and went on to earn more than $115 million in the U.S. and an Academy Award nomination for best picture.)

The real performance of "Super 8" will be told between now and Independence Day, as the movie looks to sustain whatever momentum it generates this weekend. "When you have something fresh and original, you have the opportunity to play longer," Moore said.

He cited the performance of Universal's "Bridesmaids," which opened to good business of $26.2 million on May 13 but has grossed more than $110 million, as proof that summer movies need not open huge to yield big profits as long as audiences love the experience of watching the movie.

Abrams, who directed Paramount's "Star Trek" reboot and "Mission: Impossible III," and produced the studio's alien invasion thriller "Cloverfield," felt strongly that early "Super 8" commercials and previews could not reveal one of the film's central twists, according to the person close to the production, although the studio disagreed.

To accommodate the filmmaker, Paramount's spots have emphasized "Super 8's" wistful look at the life of young boys, which consequently tilted interest toward moviegoers who were roughly the characters' same age in the 1970s. The studio's sales effort was further influenced by the film's DNA: no big names to chat up David Letterman or Jimmy Fallon, and a plot that's hard to condense in a 30-second television spot.

As an alternative, Paramount is relying on Abrams' limited but loyal fan base, a number of affirmative reviews and an unusual social media promotion to kick-start "Super 8's" debut.

On Wednesday, the studio announced that a dozen movie sites dedicated to film geeks (including Atlanta's Chud, Austin, Texas' Ain't It Cool News and Los Angeles' Slashfilm) will host sneak peeks of the film Wednesday night. At those screenings, viewers will be encouraged by a title card before the film's start to "Tweet from your seat" and share reactions to the film via Twitter.

Around the same time as those screenings, hundreds of Twitter employees will get an early look at the film near the company's San Francisco headquarters in the hope that they too will start touting the movie to their followers.

"We believe the buzz will build right then," said Amy Powell, Paramount's executive vice president for interactive marketing strategies and film production.

The hope is that Abrams' constituencies will climb on board.

"J.J. has fans from all demographics," Powell said. "He has fans from 'Alias.' He has fans from 'Star Trek.' He has fans from 'Lost.'"

Also on Wednesday, Paramount announced that "Super 8" would arrive one day early on Thursday in about 325 locations, more than half of them Imax screens, covering about 100 cities. In Paramount's thinking, it's close enough to the film's real premiere in about 3,000 locations Friday to spark ticket-buyer interest without unleashing a wave of plot spoilers.

"Word of mouth doesn't take a week anymore," Moore said. "It takes hours."

And the clock is already ticking on "Super 8."

john.horn@latimes.com