LOS ANGELES (Reuters) - After battling grandiose villains and teaming up with other superheroes, it's back-to-basics for "Iron Man" in the third installment of the multi-million-dollar franchise featuring Robert Downey Jr.

"Iron Man 3," which opens in most of the world this Friday and on May 3 in the United States, has Downey reprising his role of superhero industrialist Tony Stark from the first two films as well as last summer's "The Avengers."

Collectively, the three films have made about $2.7 billion at the global box office in the past five years.

"Iron Man 3," which continues Stark's storyline from both sets of Marvel franchises, centers around the evil extremist known as The Mandarin (Ben Kingsley) who is hell-bent on destroying the United States.

When The Mandarin destroys Stark's personal world as well as his superhero suit, Stark must begin from scratch, rebuilding his suit, freeing the woman he loves and saving the country from destruction.

Bombs go off in crowds of people and buildings are destroyed in the film that the cast says reflects real-life threats.

"We do live in an unsafe world, that's the truth," Gwyneth Paltrow, who plays Downey's love interest Pepper Potts, told reporters at a news conference this week.

"I don't think there is anything wrong with presenting that idea. We can't lie to our children and pretend the world is perfect."

Marvel's first self-financed film, 2008's "Iron Man," became a global phenomenon, transformed Downey into a superstar and set off a chain of action movies that spawned other franchises, culminating in last year's crossover film, "The Avengers."

BOWING TO CHINA

But in 2009, Walt Disney Co. bought Marvel Entertainment Inc. for $4 billion, and "Iron Man 3" is Disney's first release in the franchise.

In a first, "Iron Man 3" teamed with China-based DMG Entertainment and shot additional scenes that will only run in the Chinese version of the film, a nod to the growing importance of the Chinese movie market to Hollywood.

The cast and filmmakers have kept quiet on details of the extra scenes. But director Shane Black, who also co-wrote the script, said he was thrilled to work with "one of the single, fastest-emerging box office environments in the world."

Promotional duties have also become more creative, with Downey doing a two-week global tour for the film by making stops in Korea, Beijing, Moscow, Munich, Paris and London.

Downey said the storyline took other risks, including 11-year-old actor Ty Simpkins playing Stark's sidekick - the first time a child has been prominently featured in the "Iron Man" films.

"(Black's) idea of a superhero running into a little kid in heartland America, I think, wound up being a wise choice, and a calculated risk," said Downey.

He acknowledged the pressure that follows two successful films, saying "usually the third of any (movie) struggles to even meet the first two, let alone the first one."

But Paltrow said all three films work because of the similarities between the off-screen Downey and his brash-but-vulnerable Stark, and also owing to the actor's persistence.

"One particular strength of Robert's that we don't see on screen is the fact that he's always asking, 'What is the big picture here? How can we make it feel real?'" Paltrow said.

"I think that's why the movies keep working. They're not a weaker carbon copy of the one before." 

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