A few years ago most pundits put the prerelease Iron Man prospects under the heading of risky business.

After all, the Marvel superhero flick was directed by the inexperienced Jon Favreau and featured the wobbly actor-in-recovery Robert Downey Jr.

After its release, great reviews and a global box office of $585 million US changed all that, elevating Iron Man 2 into the rare can't-miss category when the much-anticipated sequel opens May 7 in Canada and the U.S.

That's not to say the principal players were taking things for granted as they gathered at a Beverly Hills hotel to discuss the second picture in a planned trilogy.

Present and accounted for were the vindicated power duo of Favreau and Downey Jr., not to mention Gwyneth Paltrow. Newcomers attending included Mickey Rourke, Scarlett Johansson and Don Cheadle.

"I've never done a sequel before, but for this, there wasn't the same pressure," said the 43-year-old Favreau. "We knew people were coming to the party. We just wanted to make sure it was going to be a good one."

Downey Jr. suggested he had a new set of challenges the second time around.

"It was another coming-of-age story, but in a different way," noted the 45-year-old.

In Iron Man 2, the world's aware that billionaire inventor Tony Stark (Downey Jr.) is the superhero, so the government demands that Stark share his military weapons.

Refusing to reveal his secrets for fear that the technology would fall into the wrong hands, Stark finds himself at odds with the very people he was trying to protect. Only former assistant Pepper Potts (Paltrow), who now runs Stark Industries, and Lt. Col. James (Rhodey) Rhodes (Cheadle, who replaced Terrence Howard) stay loyal.

Dastardly forces are at work even while Stark and his friends try to maintain their composure as former allies lose their patience with the mighty do-gooder.

Enter Ivan Vanko (Rourke), the ex-con son of a Russian scientist and near equal to Stark in inventiveness. Only he uses his brilliance for evil as the suited-up Whiplash, the killing machine determined to eliminate Iron Man.

Johansson shows up as Stark's new assistant, Natalie, who is really Black Widow, an undercover operative for S.H.I.E.L. D. (Strategic Homeland Intervention, Enforcement and Logistics Division). Sam Rockwell is new to the scene, too, playing the wealthy but devious arms dealer Justin Hammer. Samuel L. Jackson portrays S.H.I.E.L. D. super agent Nick Fury. Rourke's Whiplash -- an amalgamation of the comic's Blacklash and Crimson Dynamo -- is the main antagonist and he presents the role with lots of macho swagger.

"Jon [Favreau] made sure it was a great atmosphere, and I worked with some great people which made it real easy to work and have some fun," said the 57-year-old, who is enjoying a career rebound after his Oscar nod for The Wrestler last year.

Typically, Rourke did his homework for the portrayal. He visited a prison in Russia and met with a former prisoners for research, and he even speaks Russian in the film -- but that didn't come easily. "It took me about a month to learn two lines of dialogue in Russian," recalled Rourke. Whatever his method, Favreau said he did what he was hired to do. "Mickey brought a lot of intensity to the role," noted the director.

So did Johansson. She had already tried her hand at the superhero thing with her portrayal of Silken Floss in 2008's The Spirit. But she was enthusiastic about working on Iron Man 2 because her martial arts expert Black Widow wasn't there just for the curves of her tight black leather suit.

"Well, I've never really seen this kind of film where the female characters, and their sex appeal, come second," said the 25-year-old. In fact, she said Favreau insisted she make her portrayal "nuanced and presented so you could peel back the layers."

Cheadle, best known as a member of the heist crew in Ocean's Eleven, Twelve and Thirteen, agreed that it was unfortunate that he replaced his friend, Howard, who left the franchise over a salary dispute. But there were no hard feelings.

"We're cool," said Cheadle who spoke with Howard before he took the part.

Paltrow, 37, said that the cast seemed to agree that the hardships of filming Iron Man 2 were worth the extra effort. "It was like returning to a family reunion," she said.

Even the newcomers felt welcome, which Favreau said was key. He knew that Rourke, Johansson, Cheadle and Rockwell would mesh well with Downey Jr. and Paltrow on set and off.

Besides maintaining "a retrofuturistic feel" established in Iron Man, the director said the camaraderie between the actors allowed him to maintain the breezy, improvised-style dialogue, which was a highlight of the first movie.

"They were all great stewards of their characters," Favreau said.

By Bob Thompson