When exposed to sunlight, the vampires in “Twilight” sparkle. They don’t burst into flames or die horribly. Instead, their skin appears jewel-encrusted and they glitter brightly. This, tortured teen vampire Edward Cullen (Robert Pattinson) informs us, is what a killer looks like. But if the worst part about being a vampire is looking sparkly and fabulous, then what is there to be tortured about?

Not so much, apparently, which is why all the teen angst and vampiric depression in “Twilight” seems so manufactured. It’s a love story without blood and a vampire flick without bite, and that lack of substance causes “Twilight” to lose its luster quickly.

For the uninitiated, “Twilight” is based on the best-selling series of novels by Stephanie Meyer. A sort of tween girl answer to Harry Potter, the “Twilight” books (there are four in all) follow the tortured romance between Bella Swann (Kristen Stewart) and Edward Cullen. The pair live in Forks, a small town in Washington state where it’s overcast and rainy so often that Cullen and his family of vampires have decided to set up shop permanently. The patriarch of the vampire clan is a respected doctor in town and the family curbs their appetite for human blood by dining on deer and other wildlife. Bella is new to town, moving in with her father (Billy Burke) after her mother decides to move to Florida. Girl meets vampire, they fall in love, some other vampires show up, and before you know it, it’s prom night.

“Twilight” never gets more complex than that, and while you can pad out even the thinnest-plotted novel with all sorts of nonsense, the same tactics can’t be used in film. No matter how many times Bella and Edward proclaim their love for each other (and it happens to a nauseating degree), the protestations are hollow and unconvincing. It’s partly due to Pattinson’s weak acting—he maintains a constant drowsy, just-out-of-bed appearance—but it’s also because the characters have known each other for all of a week. Edward claims his sudden attraction to Bella is because of the unique scent of her blood and the fact that he can’t read her mind. In addition to super strength, heightened senses and immortality, these vampires are also telepathic, further making vampirism a pretty sweet gig. As for Bella, she loves Edward because he keeps saving her from danger—improbable car wrecks and conveniently timed attacks by drunk frat guys—a damsel-in-distress plotline that gets old fast.

All the relationships and interactions in “Twilight” are superficial. Characters suddenly become best friends or bitter enemies, sometimes both within a few moments. All that gloss and sheen is fine as long as no real drama is called for. But in a movie fraught with melodrama, there’s got to be a reason to care about whether the characters live, die or turn into vampires, and “Twilight” is short on good reasons for anything.

To make up for it, director Catherine Hardwicke keeps the film moving fast, zipping from one uninteresting scene to another, perhaps hoping speed will make up for the lack of suspense and tension. It doesn’t, instead making “Twilight” seem like a music video that never ends. The sprawling cast is made up of relative unknowns and the results are fair to poor. Stewart has some potential, but Pattinson and the other vampires are forgettable at best.

The weak characters and embarrassing dialogue might all be forgivable if there was at least some solid vampire action to build on. But the vamps in “Twilight” are essentially de-fanged. The Cullen family is not dark, mysterious or evil. Apart from some pale skin, they look like they could have walked out of a J. Crew catalogue. Edward and company have a strict no-eating-humans policy (they call themselves vegetarians), and a simple stake through the heart can’t kill them—instead, vampire hunters must tear a bloodsucker limb from limb and set it on fire, which sounds pretty labor intensive. The seduction of the innocent has always been the engine that drives vampire fiction, the pure young human struggling to resist the allure of the evil monster. But the Cullens play family pick-up games of baseball and get along with humans pretty well. Once you factor out the evil, the death-by-sunlight thing and the whole bit about drinking human blood, there really aren’t any downsides to being a vampire. Immortality, superpowers and a glittery complexion? Sign me up already.

“Twilight” isn’t much more than a pair of plastic vampire fangs slapped onto an unconvincing love story. But will any of that matter to teen girls, the only audience excited about “Twilight”? Probably not. Love without complications and vampirism without consequence—with some sleepy-eyed dreamboats thrown in for good measure—is a formula too enticing to pass up. Jaded cynics and serious vampire fans will avoid “Twilight” on instinct. But others will have to learn the hard way that, unlike the vamps on screen, “Twilight,” quite simply, bites.