What's riskier for Smith: vampires or a one-man show?

HOLLYWOOD — Last year, they shut down New York for a few hours so Will Smith could be alone.

It came neither easy nor cheap, snarling traffic and making more than a few people very angry in the process. But one busy Monday morning in October 2006, a production crew for the sci-fi drama "I Am Legend" cordoned off several blocks of Manhattan's Fifth Avenue and completely depopulated the area so the Oscar-nominated star of "Ali" could be filmed walking cautiously down one of the city's most traveled arteries in total solitude — his surroundings utterly and perfectly still.

"That was aggressive. I don't think anyone's going to be able to do that in New York again any time soon," Smith said, breaking into a wide grin at the memory. "People were not happy. That's the most middle fingers I've ever gotten in my career."

Nobody said it was going to be easy portraying the last man on Earth — a military scientist who survives a biological pandemic that apparently has turned the rest of humanity into night-crawling vampire zombies. Over the previous 12 years, a panoply of A-list actors had been attached to the role — notably Tom Cruise, Michael Douglas and Arnold Schwarzenegger — but until Smith came along, none could shepherd the high-concept project into production.

Sticking Point A: The "Legend" protagonist is an island unto himself, spending his daylight hours trying to concoct an antidote to vampirism and retiring to his locked and loaded Greenwich Village brownstone at night when the freaks come out for blood. That means, for much of the movie — even when backdropped by quintessential Big Apple locations including Washington Square Park and Times Square — he's the last man on-screen.

Smith has bumped up against the apocalypse in movies before, battling legions of murderous androids in "I, Robot" and intercepting marauding aliens set on conquering Earth in "Independence Day." "Legend," however, represents a risk for one of the biggest movie stars in the world. Reportedly budgeted at more than $100 million, it's a big-budget one-man show in which he's seen emoting opposite a dog, various mannequins and computer-generated monsters. Think "Castaway" meets "28 Days Later."

"It is an extremely delicate balancing act — not going too far one way or another," Smith said, dripping with movie blood now on the set of his postmodern superhero flick "Hancock." "The second you have one too many explosions, one music cue a little too high, you destroy it. You lose it all."

Since combining forces with screenwriter-producer Akiva Goldsman and director Francis Lawrence on the project in 2005, the stated ambition with "Legend" has been to cross-pollinate summer blockbuster-style eye candy with the gravitas of an awards-season Serious Film.

But "I Am Legend," which opens Friday, arrives as the third big-screen iteration of celebrated "Twilight Zone" writer Richard Matheson's popular 1954 science-fiction novella of the same name. "The Last Man on Earth," a low-budget version shot in Italy and starring Vincent Price, was released in 1964. In 1971, the material was reworked again in the service of "The Omega Man," which pitted Charlton Heston against a clan of psychotic albino mutants. Matheson's book also has been cited as a primary influence on precisely the sort of genre movie "Legend" wants nothing to do with: George Romero's 1968 zombie masterwork, "Night of the Living Dead."

Since 1997, a who's who of big-deal action and genre directors has flirted with remaking "Legend," among them: Ridley Scott, Guillermo Del Toro and Michael Bay, who was set to begin filming "Legend" with Smith in 2002 when the project was pre-empted by British director Danny Boyle's cerebral horror fantasy "28 Days Later." That film depicts a similarly disease-ravaged, post-apocalyptic wasteland — replete with depopulated London locales — in which a trio of heroes who likewise may be the last people on Earth battle flesh-eating zombies for survival.

The project's colorful development history left Lawrence — director of "Constantine," the hit 2005 comic-book adaptation starring Keanu Reeves as a supernatural detective who battles Satan — feeling somewhat apprehensive about mounting his own adaptation of "Legend."

"There's been some big talent attached," said Lawrence, on break from final editing of the film. "So people in the business are waiting to see it, wondering how (the other directors) would have stacked up. In terms of mass audience, I'm not daunted at all. But people in the business are daunting to me."

For Smith, who says he has felt compelled to have his movies "mean something" since topping the box-office chart with his inspirational father-son drama "The Pursuit of Happyness" last year, the movie was a splashy way to pose certain big existential questions.

"The sneaky secret is that this one is Job," Smith said of his character in "Legend." "You take a man, take everything from him, and can he find a reason to continue? Can he find the hope or desire to excel and advance in life? Or does the death of everything around him create imminent death for himself?"

The actor paused for a moment, then added, "The question is, can you do that with a wonderful character piece wrapped in blockbuster clothes?"