Exclusive: This is 'Iron Man'

PUMPING 'IRON' Downey Jr.'s costume, designed by Oscar-winning F/X guru Winston

Iron Man is the latest Marvel Comics superhero to jump from splash page to big screen. (The film is due May 2008.) Director Jon Favreau (Elf ) began shooting in March with star Robert Downey Jr. — in his first comic-book role — as the man inside the cybernetic Mark III suit (pictured) and Gwyneth Paltrow as his trusted assistant. In the film, Downey plays Tony Stark, a playboy industrialist who decides to don high-tech armor to fight baddies after suffering a life-threatening heart injury in war-torn Afghanistan. ''This is a decidedly adult superhero story,'' says Favreau. (Fanboy FYI: Look for Stark's legendary drinking problem to pop up in possible sequels.)

Faithful to the comics and constructed by Oscar-winning F/X maestro Stan Winston, the Iron Man togs — a far cry from Stark's normal black-tie attire — are robo-cool but make for restrictive, sweaty duds. ''Robert was very bullish on wearing the suit whenever possible,'' says Favreau of his star, who bulked up for the role. ''Now I don't know if he's such a fan of that idea.''