What a difference a year can make -- especially in Hollywood. When I visited the downtown Los Angeles set of Transformers last September, star Shia LaBeouf was every bit the scrappy, exuberant kid I remembered from movies like Constantine and I, Robot. Since then, LaBeouf has gone from the perennial sidekick with the funny-sounding name to a bankable star with a number one movie under his belt (the surprise hit Disturbia) and a major role in a little Steven Spielberg flick called Indiana Jones 4.

Now, on the eve of the eagerly-awaited July 3rd release of Transformers, the weight of the young actor's meteoric rise to fame is evident on his face: a little dazed, a little weary, a little overwhelmed. Splitting time between his work on the Indy 4 set and his promotional duties for Transformers, the 21-year-old hasn't had a chance to process it all. "It’s crazy," remarks LaBeouf, searching in vain for a more apt description. "A few times you’ll just catch me with nothing else to say. I don’t know what to say about it. I don’t know how it happened or what’s going on."

One might have expected him to be a little more prepared for the newfound success. Having worked in the industry since his pre-teen days, LaBeouf is already a Hollywood veteran. "You never expect it to explode like that though," says LaBeouf. "The Indy news alone would have been my year, my life. And nobody expected Disturbia. It wasn’t like people were eyeing that like that was going to be a big hit or anything."

Unlike Disturbia, Transformers arrives in theaters carrying with it the lofty expectations associated with a film produced by Steven Spielberg and directed by Michael Bay. LaBeouf stars in the film as Spike Witwicky, a gawky misfit who becomes the Autobots' greatest ally in their war against the sinister Decepticons.

The role called for LaBeouf to perform a number of hazardous stunts -- par for the course on a Michael Bay set. As an action director, Bay is known to prefer real, in-camera effects, as opposed to the computer-generated variety. It's a decidedly old-school approach that exposes actors to a variety of perilous situations. On the set of Transformers, LaBeouf says he feared for his life "every day. You look at Bay and he's all frantic: 'Put him on the thing. Put him on the thing!' That’s scary because you’re moving so fast. You don’t want him to mess up and forget that you’re on the thing."

Bay's famously brisk pace required Transformers castmembers to be on their toes. It wasn't unusual for the director to toss out pages of dialogue and instruct his actors to improvise entire scenes instead. "Most of it was just like, ‘Just go. We’ve got to spice this up, make it funnier. Let’s do this and this,’" explains LaBeouf. "It's collaborative, like a big collage. Everybody jumps in with their ideas and throws stuff in. I wasn’t the only one. Voight and Turturro and Megan, everybody."

While LaBeouf enjoyed a few scenes with legends Jon Voight and John Turturro, more often than not his on-screen companions were skinny poles with glowing balls attached at the top -- props used to signify the computer-generated robots that would be added during post-production. "You have choreograph it like a dance," LaBeouf says of working with the imaginary robots. "You just start learning movements -- ‘On whose line is this happening?’ or ‘Where’s it coming from?’ Then you just start memorizing their movements. It becomes fun."

Risking one's life each day on the set of Transformers wasn't without its perks, the greatest of which was the opportunity to hang out with a certain living legend named Spielberg. "He came to set and said ‘Hey, Shia, how’s life? Movie looks great,’" relates LaBeouf. "He’s always really pleasant and trying to make you feel comfortable all the time. He’s super aware that he’s Steven Spielberg and what that does to a person." The meeting must have made an impression with the director. Soon afterward LaBeouf was invited to join the cast of Indiana Jones 4.

Indy 4 is set for a Summer 2008 release; expect production on a second Transformers movie to begin shortly thereafter. Though planning for another film is still in its infancy, LaBeouf, who is signed on for two more Transformers films, knows what he doesn't want to see in a sequel. "I don't want to go into Beast Wars world; that would be strange," says LaBeouf. "There's a little bit of it with Scorponok, but it's not nuts. If they went nuts and it was like gorilla-giraffe fights, that'd be lame."

Check out ReelzChannel.com's Transformers page for dozens of clips, images, interviews and more!