Robert Downey Jr. Talks Iron Man 2

"The film is almost entirely about character, and yet we still have twice as much action as we did last time, so it's going to be nuts," Robert tells our own Thea Andrews of the super sequel, set to start filming Monday. "Essentially Iron Man 2 is about looking behind the armor, or the armature, of a superhero. It's one thing to say you're Iron Man, it's another thing to be fully ready to do that."

Robert says he's no longer on his strict Sherlock Holmes diet and has returned to some serious iron to once again portray Tony Stark: "I'm on Beefcake Charlie status," he jokes. "I've got to not be the skinny Brit anymore. I have to be the Tony that you know and may have loved."

As for co-star Scarlett Johansson, who plays the femme fatale Black Widow in the sequel, Robert says, "We've been rehearsing and she's in insane shape. She's getting lean and mean."