The ‘Star Wars' universe landed in London on Wednesday, with stormtroopers standing guard at the riverside Tate Modern art gallery. They had their blasters ready for the launch of the sci-fi franchise's new standalone film: "Rogue One: A Star Wars Story."

The movie does not follow the trilogy that began with last year's "The Force Awakens" box office blockbuster. Rather, it is the first spin-off in the space saga's reboot since Disney bought Lucasfilm Limited for U.S.$4 billion in 2012.

Felicity Jones stars as new heroine Jyn Erso, who bands together with other rebels to steal plans for the massive weapon of destruction, the Death Star.

"I look back at those early films and use them as inspiration, but I definitely wanted Jyn to be her own person. Actually, one of the greatest references was looking at Harrison Ford, and there were certain sequences that I'd seen in his work that were really helpful. Watching the ‘Star Wars' films and then in ‘Indiana Jones,' he always manages to make whatever he's doing seem really fun," Jones said.

"Rogue One" is set before George Lucas's 1977 "Star Wars: Episode IV—A New Hope." It also stars Mexican actor Diego Luna, Chinese actor Donnie Yen and British-born actor Riz Ahmed.

"Our film is the most grounded ‘Star Wars.' It's a film about the people. This happens in the darkest times of the galaxy when there's no Jedis around. It's the people who have to come out and fight for freedom. I love that. I think it's a good message to send today," said actor Diego Luna.

"It both respects the ‘Star Wars' heritage, but it's also doing something quite different. Kind of breaking the mould in many ways. It's got a lot of grit and edge to it. So, hopefully there's something there for everyone," Ahmed said.

The movie, which hits cinemas worldwide from Thursday, has split movie critics. Nevertheless, it is expected to make more than U.S.$300 million at the global box office this weekend.