The love-after-death movie “Twilight” is going to be so huge it would take a stake through the heart to stop it. And the reasons seem so obvious they make you say, “D’oh!”: a heavily computer-generated, blood-flecked, teenage soap opera set in the hormonal chaos of high school. A ready-made fan base of rabid Gothic/chick-lit readers cultivated by Stephenie Meyer’s four-book series. And a not-so-secret weapon named Kristen Stewart.

The actress, who is just old enough to have voted in the recent election, is no newcomer. “If that were the case,” she says, “I’d be tripping.” No, her filmography began when she was 11 (in “The Safety of Objects”), and her roles include playing Jodie Foster’s daughter in “Panic Room” (2002), making a big splash in the adventure “Catch That Kid” (2004) and being the best thing in several movies (including last year’s “The Messengers”).

But “Twilight” promises something new and presumably wonderful. Adapted from the Meyer books by Melissa Rosenberg – rest assured, there will be sequels – “Twilight” is set in Forks, where Bella Swan (Stewart) has come to stay with her police chief father (Billy Burke) and become reacquainted with a town filled with people she hasn’t seen in years – and others, the likes of which she’s never seen.

They are namely, the Cullens, an ad-hoc family of white-complected, crazy-eyed outsiders who are accepted, more or less, by the rest of the student body (sort of the way Michael Jackson might be, should he re-enroll in high school).

From the moment they meet, Bella and Edward Cullen (Robert Pattinson) walk a razor’s edge between attraction and loathing and experience a magnetism so strong it repels. Ultimately, in a process that develops more quickly than it does in the books, Bella is exposed to the Cullen family and their unorthodox dining habits.

Director Catherine Hardwicke (“Thirteen”) employs enough violence and gymnastics, both real and computer-generated, to keep boys interested (“It wasn’t until I was up in the air that I realized I was so uncoordinated,” said co-star Nikki Reed). And unlike most movie shoots, the absence of light was an asset. “The production was very weather-dependent,” said Peter Facinelli, who plays clan chief Dr. Carlisle Cullen. “As soon as we had clouds, we had to go.”

The undead, as we all know, abhor direct sunlight.

But the movie is a romance, one that serves as an exalted metaphor for the hysteria of adolescence.

“In my role, I’m a child,” said Stewart. “He’s not – he’s 108 years old. But I’m playing a child who has never had to give as much as she’s giving to another person and sometimes that did feel entirely goofy.”

The full-blooded dialogue of “Twilight” does, at times, feel a bit engorged.

“Sometimes, I’d be like, ‘This is crap. This is the worst, most trite piece of crap I’ve ever done in my life,’” Stewart said, laughing. “I love the books, but trying to do it in real life, it doesn’t translate.”

As unguarded as Stewart seems to be about the content of “Twilight,” she’s utterly realistic about what it’s going to do for her career.

“It’s the first movie I’ve done that has gotten so much notice,” she said. “And it doesn’t even have to be good. If the movie flops, we’ll get just as much press for like, ‘Wow, I can’t believe that movie was horrible and it flopped.’ You know?”

She sits up. “This makes my life a lot easier, in a way. I’m not going to have to say, ‘Oh, I want to do that movie so bad, but they have no money and I’m going to be too old by the time they get the money and I’m not going to be able to play the part.’ That’s not the case now – I get to do things I’m really passionate about.”