Fast action hero

SHIA LaBEOUF’S first day on the “Transformers” set nearly killed him.

“We had these police guard dogs,” says director Michael Bay, standing in the shadow of a truck loaded with Furby toys and rigged with 50 explosive devices in downtown Los Angeles. “I didn’t know how dangerous they could be.”

“Thank God I’m really fast,” LaBeouf says. “He’s telling me, ‘Don’t worry. It’s safe.’ Action gets called. Attack dogs run, run, run, run! First take goes great. Second take goes great.”

Bay jumps back in: “Third take, he just locked eyes on Shia and kept going.”

“Ran past the [trainer] with the arm brace and chased me around the set,” LaBeouf says. “They had to attack the dogs. They had to tackle them. The dog was 200 pounds. They would’ve killed me. It would have been somebody else in the part. Yeah. Welcome to ‘Transformers.’ ”

Bay explodes with laughter. LaBeouf beams. He has officially joined that most macho of Hollywood fraternities: He has been inducted as a Michael Bay leading man.

Based on a popular 1980s Hasbro toy, the $145-million film (opening Tuesday) stars LaBeouf as Sam “Spike” Witwicky, a 17-year-old who buys his first car, a slick yellow Camaro, only to discover that it’s really a shape-shifting alien robot named Bumblebee from the planet Cybertron. And it’s not by accident that Spike has landed himself such a sweet ride -- both the good Autobots and evil Decepticons need a Witwicky family heirloom to guide them to their life source, the All-Spark.

Meanwhile, the Decepticons attack a military base in Qatar manned by two commanders (Josh Duhamel and Tyrese Gibson), and the government assumes that all alien robots are terrorists and rushes into conflict. The movie, one of the summer’s few nonsequels, has been building steady enthusiasm among teens.

Executive producer Steven Spielberg pitched the story to Bay as a return to the Amblin tradition of movies such as “E.T.,” in which kids are privy to a world of wonder unknown to adults. Bay hesitated, fearing it would be a stupid toy movie, but ultimately saw the project’s potential. “What I really like in this movie is there’s this magical connection between the kids and the robots,” he says.

On this late September day while filming last year, the chief connections being made are between weapons and their targets. Navy SEALs fire bazookas, burned-out cars litter the street and two Black Hawk helicopters blaze across the sky. Amid this choreographed chaos -- or “Bayos,” as the crew calls it -- skinny, doe-eyed LaBeouf dodges bullets and darts through columns of flame.

Although he may look like a lost indie actor who took a wrong turn at his last Dito Montiel movie, LaBeouf is hardly an accidental action hero. “I put the fishers out that I wanted to do a big pop film,” says LaBeouf, who will next star in the fourth installment of “Indiana Jones.” “I didn’t want to Christina Ricci my career.”

Apparently, he was willing to sacrifice his body in the process. The just-turned-21-year-old actor sustained plenty of bruises while hanging from the side of a building and skidding down the street on a Teflon plate. Of course, he can’t say he wasn’t warned; Bay guaranteed him up front that he would get hurt during filming, and he’s gotten off relatively lightly compared to some of his costars.

“I’ve been running and rolling around on the ground and driving tow trucks,” says Megan Fox, who plays Spike’s love interest, Mikaela, a character named after Spielberg’s daughter. “I’ve lost my toenails from doing all these things in motorcycle boots. I’ve slipped discs in my back. I got burned. I got a couple of cuts and scars. It’s crazy, but you also feel like a soldier.”

The real soldiers didn’t fare much better. “Tiny tore his knee up carrying a guy on his shoulders,” says Duhamel, indicating an ironically named Navy SEAL. “He’s got to get surgery after we’re done.”

The war-zone atmosphere that Bay cultivates has its upside. When LaBeouf runs into former Bay leading men such as Will Smith or Ewan McGregor, an instant bond exists. “I was doing ‘Disturbia’ with David Morse, who had done ‘The Rock’ with Mike,” says LaBeouf. “He’s like, ‘Get arnica gel.’ It’s a homeopathic gel that you rub on bruises and the bruise goes away the next day. I mean, literally, I’ll soak in Epsom salt three hours a night because your muscles, they just start freezing up.”

But LaBeouf won’t complain. After working with Smith on “I, Robot” and Keanu Reeves on “Constantine,” he has tried to follow their upbeat examples and be a cheerleader for the cast and crew. “You got to keep everyone up and awake,” says LaBeouf, “because when you’re not awake on this movie, you can die.”

True to his word, he has the crew in stitches during his next scene. After diving in front of a black Escalade to retrieve the All-Spark from under its wheels and being called a “jerk” by its pretty blond driver, he incorporates a bold improvisation by giving her a big, unscripted kiss.

“Jerk!” yells Bay, grinning broadly as he appropriates the scene’s only dialogue. “We’re not using that one.”

“With me, it’s like a friendship,” LaBeouf says proudly of his relationship with the notoriously difficult Bay. “He’s never been better with any other actor. And so, yeah, I came to the set thinking, ‘Oh, here are all these stories.’ And then you get here, and that’s not the case. He’s our Gen. Patton.”

Bay does operate with a ruthless efficiency rarely seen on movie sets, where the standard practice is “Hurry up and wait.” “He’s shooting more in one day than most directors shoot in a week,” Gibson says. Bay speeds from one setup to the next, hopping into a golf cart when his legs can’t keep pace. His director’s chair is lavishly padded, but he never sits in it. One minute, he’s berating 200 extras for botching their slow-motion walk-through of a scene. The next, he’s kvetching about a nearby house of worship that requires silence during its services: “Church is killing me.”

Bay barks orders into his bullhorn, which is emblazoned with: “Warning! Not to be used when upset. Will void warranty.” Given that the director has smashed dozens of these over the course of his career, it’s a joke containing more than a kernel of truth.

A ‘nervous little gremlin’

AS soon as church ends, Bay gives the go-ahead to ignite the devices in the truck. After a blink-and-you’ll-miss-it countdown, it’s raining charred Furbies -- another Hasbro toy of the same era -- and green smoke is rolling through the streets. Bay pulls his black polo shirt over his mouth. He may be a tough guy, but he’s still concerned about the massive amount of debris he’s inhaled over the course of his explosive career. “I think I’ve got to get more contacts because I’ve got to take these out,” he tells a production assistant. “Can you get my glasses?”

Truth be told, the bespectacled Bay, as he enters his fourth decade, is actually a touch mellower than his young star.

“I freak out sometimes,” LaBeouf admits as a tank rolls by the Orpheum Theatre. “When I’m in my trailer, I have panic attacks. I’m like a nervous little gremlin. [On set,] I can control myself. I can watch the monitor and say, ‘That’s the person I’ve created. That’s who I want to be right now.’

“Acting is my entirety. This is the most important thing in life to me -- above politics, above my family, above my own happiness. If I didn’t have it, I wouldn’t want to live, literally. I’m saying this and I mean it. Happiness isn’t worth anything. It’s momentary. This is forever.”