AFP/ Los Angeles

With little more than a week to go before "Star Wars: The Force Awakens" hits theaters, the plot of the hotly anticipated film is still a closely guarded secret. But director J.J. Abrams promises it won't be a nostalgic trip down memory lane.

The latest installment of the blockbuster sci-fi saga -- the first in a decade -- opens in US theaters on December 18 and keen fans can't wait.

The cast -- beloved veterans of the original films Harrison Ford (Han Solo) and Carrie Fisher (Princess Leia), as well as fresh faces joining the franchise -- gathered in Los Angeles on Sunday at an undisclosed location.

But they didn't let much slip.

"I wanted to keep audiences surprised," Abrams told reporters.

The director, also known for his successful reboot of the "Star Trek" films, added: "It's not a nostalgic trip -- we had to go back in order to go forward."

"The Force Awakens" -- Episode VII in the saga -- takes place 30 years after "Return of the Jedi."

"Star Wars" has attracted generations of loyal fans ever since the first film arrived nearly 40 years ago, creating a signature moment in the history of pop culture and launching one of the biggest movie franchises ever.

It turned Ford, Fisher and Mark Hamill (Luke Skywalker) into stars overnight.

Ford said it didn't take much to step back into Han Solo's boots.

"I was interested in the described path of the character ... it was easy," he said.

"It's gratifying to be part of this," he added. "It's always nice to anticipate working in something that you know people will have an appetite for."

"And it's fun to play with these toys again," he joked.

Han Solo returns among other things to bridge the future with the past.

Not to be forgotten are the beloved droids R2-D2 (Kenny Baker) and C-3PO (Anthony Daniels) as well as Chewbacca (Peter Mayhew), Han Solo's Wookiee co-pilot.

Luke Skywalker is among the great unknowns of the new movie. The Jedi master is notably absent from the official poster and Hamill -- who features in the film's credits -- did not attend Sunday's press conference, building suspense.

- Strong women -

The film's new faces include Oscar winner Lupita Nyong'o and rising Hollywood star Oscar Isaac, as well as virtual British unknowns John Boyega and Daisy Ridley.

"The Force Awakens" features several new female leads.

The 23-year-old Ridley plays the scavenger Rey, one of the main characters.

What we know so far is that, since the age of five, Rey has lived alone on the desert planet Jakku and been left to her own devices in order to survive.

"She's brave, she's vulnerable," Ridley said.

Another movie mystery are Rey's roots. Her last name has not been revealed and there is some speculation about a possible link to Princess Leia, Han Solo or Skywalker.

Gwendoline Christie, who made a name for herself in "Game of Thrones," personifies Captain Phasma, one of the film's villains.

Nyong'o, meanwhile, will slip into the skin of pirate Maz Kanata, for which the actress used motion-capture technology.

"I could work with my body in new ways," she told reporters.

With fans counting down to the film's opening, industry experts are predicting it will be a massive hit -- at the box office and beyond. 

Advance ticket sales already smashed records two months before the release and analysts expect merchandise sales to reach up to $5 billion this year, with everything from lightsabers to action figures and even pet gear on offer.

"I'm aware of the value that's placed on these films by the audience and I'm gratified that they had been passed on generationally through families and that there's still an audience," Ford said.