Growing up, Iron Man was one of my favorite comic-book superheroes -- and come 2008, I may be able to watch ol' Shellhead in action on the big screen. Last week, Marvel Entertainment (NYSE:MVL) announced plans for a May 2008 movie debut for its armor-clad adventurer.

Actor Jon Favreau -- best known as the yin to Vince Vaughn's yang in Swingers and, more recently, The Break-Up -- will direct, while former Marvel Studios head Avi Arad will produce the film. But that's only if investors can be convinced to pony up the cash.

According to the press statement, Marvel expects a $525 million credit facility funded by Merrill Lynch (NYSE:MER) to finance the film. Unfortunately, that deal, struck in September, never included Iron Man among the list of characters that would secure the loan; lesser-knowns such as Hawkeye, Ant-Man, and Doctor Strange were named instead. That means investors must approve using the funds for the Iron Man project before a portion of the credit facility can be released.

For its part, Marvel remains confident, with good reason. Favreau is no stranger to far-flung films, having appeared in both Batman Forever and Marvel's somewhat-successful screen adaptation of the blind hero Daredevil.

Still, Iron Man won't be an easy film to make. Just take a look at the armor. Sure, computer-generated graphics have advanced considerably, but how do you make a guy who looks like a robot act human -- even in combat?

The political undercurrents that have followed the character throughout his comic-book history are even more complicated. If Favreau stays true to the intentions of Iron Man's creators, then billionaire industrialist Tony Stark will be an onscreen version of Defense Secretary Donald Rumsfeld: unapologetically conservative, and ready to take the fight to the enemy by any means necessary. If the war on terror remains a political hot potato in 2008 -- and I'm guessing will be -- Iron Man could be a very expensive casualty.

On the other hand, Stark is as flawed a character as any in Marvel's vast universe. He's at times a lunatic, an alcoholic, a murderer, and a pariah. He can be both selfish and selfless. In short, he's complex, as most great characters are. That leaves Favreau a lot to work with.

Unfortunately, he's yet to prove consistently capable of turning great material into a blockbuster. Favreau scored big when he directed the hit Will Ferrell comedy Elf. But his next project, the screen adaptation of the children's book Zathura, didn't even make enough to cover production costs, according to Box Office Mojo. That's worrisome. I mean, if Marvel's last two major films -- X-Men: The Last Stand and Fantastic Four -- are any indication, Iron Man will cost at least $100 million to produce.

For me, Marvel is the most intriguing stock among all the picks David Gardner has made for Motley Fool Stock Advisor. But should you invest? Not if you're uncomfortable with risk. After all, either Tony Stark could show up in theaters in 2008: the hero or the drunk. If it's the former, today's investors should be richly rewarded. If it's the latter, well, at least you've been warned. Good luck, Shellhead. You're going to need it.

Marvel is a Motley Fool Stock Advisor selection. A freeall-access passgets you a backstage look at all of the stocks that are helping David and Tom Gardner beat the S&P 500 by more than 30% each as of this writing.

Fool contributor Tim Beyers hopes ol' Shellhead comes off well on celluloid. Tim didn't own shares in any of the companies mentioned in this story at the time of publication. You can find out which stocks he owns by checking Tim's Fool profile . The Motley Fool has an ironclad disclosure policy (though it doesn't come with repulsor rays).