The promotional poster for “Walking Tall” makes the second half of the movie’s title look like the understatement of the year. In the image, Dwayne “The Rock” Johnson, who stars in the movie, looks like a titan. “Tall” just seems too modest to describe “The Rock,” whose persona radiates Herculean strength and unabashed machismo. But Johnson (who, incidentally, is slightly less enormous in person) will be the first to point out that both he and his new movie are about much more than size.”I actually went to the studio with this — they didn’t seek me out,” he eagerly explains. “Walking Tall,” which opens nationwide today, is an updated version of the 1973 film by the same name and is based on the life of Tennessee Sheriff Buford Pusser. Johnson’s character is renamed Chris Vaughn and the setting is shifted to rural Washington for the remake, but the story remains the same: a war hero returns to his hometown to find it marred by corruption. Determined to rid the place of drugs, poverty and crime, Vaughn takes matters into his own hands.

Johnson maintains that he is a “huge fan” of the original movie and that he feels that Pusser’s legacy will appeal to today’s audiences as well. “I chose the role because I love the movie,” he says. “It inspired and moved me.”

But making “Walking Tall” also meant taking on a breakout role for Johnson, whose repertoire to date has been one of physical spectacles. His successful stint in “The Mummy Returns” led to a spinoff starring role in “The Scorpion King,” and both these films and last year’s “The Rundown” were built around displays of Johnson’s muscle.

Working on “Walking Tall” was “all about taking smaller steps to get better as an actor and not being afraid to try a movie that had a little drama in it,” Johnson says.

Attempting drama, it turns out, has inspired Johnson to pursue other acting genres as well. He will tackle comedy in his next project, “Be Cool,” a sequel to 1995’s “Get Shorty.” Uma Thurman and John Travolta headline the film, supported by a curiously eclectic but gifted cast: Danny DeVito, Steven Tyler, James Gandolfini, Outkast’s Andre 3000, Vince Vaughn and Cedric the Entertainer have all signed on. Johnson plays a gay bodyguard desperate to get into show business. He admits that the part is a radical departure from his usual roles. Just in case his onscreen singing and dancing are too convincing, he says, the arching eyebrow that has become the wrestling trademark of “The Rock” will make an appearance in the movie.

The public has been seeing less and less of that eyebrow these days, as Johnson’s adventures in the world of professional wrestling have taken a backseat to making and promoting movies. Still worn out from attending Wrestlemania XX the night before, Johnson insists that wrestling will always be foremost in his heart. “I love wrestling because I grew up in wrestling, so I have a passion for it,” he says. But he also laughingly confirms that the “acting bug” is, in fact, real — and potent. “It was like two minutes on screen [in “The Mummy Returns”] and then I was like, ‘Wow, this is amazing. This is really, really cool.'”

Johnson may be anxious to further his film career, but producers should be cautioned that having him on location may inspire unforeseen expenses. One afternoon with Johnson on the set of “Walking Tall” set MGM back for the cost of a Porsche. While filming a scene in which he confronts the movie’s sleazy villain, Johnson misunderstood the director’s cues and clobbered the back of the brand new car with a heavy wooden club. “I wasn’t actually supposed to smash the taillights,” he recalls with amusement. “There’s this long silence, and then I hear on the bullhorn ‘I don’t think you were supposed to smash the Porsche.'”

The original “Walking Tall” inspired two sequels, but Johnson says the thought of continuing the venture hasn’t crossed his mind. A “Walking Tall” series would certainly provide ample opportunities for Johnson to become the supreme action hero of the next generation. He stands to face some tough competition from young, popular tough guys like Vin Diesel. But Johnson is hardly intimidated by the prospect of a faceoff with Diesel. “Yeah, that’d be a good ass-whupping for him,” he playfully scoffs.

But behind the booming bravado that has become his defining attitude, Johnson still seems to worry less about solidifying his jump from the B-list to star status than he does about the effect that “Walking Tall” will have on audiences — particularly on his fans. He clearly hopes that the film will prove his talents and communicate his morals. The underlying theme of “Walking Tall” draws from the famous words of President Teddy Roosevelt: “speak softly and carry a big stick.”

Reflecting on the philosophy, Johnson grows quiet. “I love that,” he says solemnly. “I believe in it.” In the moment, the thunder of “The Rock” is replaced by the humble earnestness of an artist who has just completed something he has real faith in. Johnson wants to be seen as a serious actor, and right now he looks the part.