The secret to the success of 2008's 'Iron Man'? The unexpected delivering big time: Robert Downey Jr., action star? Gwyneth Paltrow meets CGI? Director Jon Favreau trading in swingers and losers for superheroes? Yes, yes and yes.

But how do you make a sequel just as fresh? Start with the villain and cast an actor pulling off a Downey-esque comeback of his own ('The Wrestler' himself, Mickey Rourke, as villain Ivan Vanko.) 'Iron Man 2' also includes some back story on Tony Stark, the complicated, armor-coated do-gooder played by Downey. 'Mad Men's' John Slattery shows up in flashbacks as Stark's hip dad. Rounding out the cast are Don Cheadle, Samuel L. Jackson and Scarlett Johansson.

Downey is coming off a Golden Globe win for another big budget effort, 'Sherlock Holmes.' There's probably no other actor right now who can jump so seamlessly between studio tentpoles and the award-worthy ('Good Night, and Good Luck' and his 2008 Supporting Actor nomination for 'Tropic Thunder.') Of course, the star of 2008's Best Picture will try to do just that next month when 'No Country for Old Men's' Josh Brolin takes on DC Comics' 'Jonah Hex.'

Critics can be a sequel's biggest nemesis -- let's see what they're hurling at Iron Man.
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