Skipping the preface, cause it's crap. Basically Bella's all "Aaah! I'm gonna die and stuff!"
Anyway. So Bella Swan is this chick and she's totally not pretty, except she really is, she just thinks she isn't pretty, you know? Bella is also really awkward and clumsy, but it's stinkin' adorable. So anyway, she moves from Alaska or Argentina or something (I forget) and she's all bummed because her mom married a baseball player guy. It's really sad. But it's okay because her dad buys her a truck! And she really likes the truck, even though it's, like, ugly and stuff. It's red.
Okay so fast forward to the next day, Bella has to go to school and she's embarrassed cause her truck is TOTALLY loud. But it's okay because all the other cars are really ugly except for this really shiny Volvo car, and that's cool because a Volvo isn't even that great. So yeah, the truck totally still rocks. So then Bella goes inside and there's some dumb stuff with people or whatever, and this Mike kid really likes her, but then Bella sees this guy named Edward. Bella is really cute because she's so awkward and clumsy.
Edward is really dreamy sexy hot. Bella talks about it all the time, and he has glittering gold eyes that probably ooze unicorns, but Bella never mentions that. I bet it's true though. Bella can be so unobservant. Also, she's awkward, and pretty clumsy.
Edward doesn't really like Bella at first, because she smells YUMTASTIC and he wants to eat her. Because, guess what? This is the best part. You know dreamy sexy hot Edward? Well, surprise twist, he's a VAMPIRE! Only don't worry, he only drinks animal blood instead of human blood and for some reason that makes his eyes sexy hot gold instead of red. Because that makes sense. It's not confusing at all that the type of blood ingested correlates to eye color. I like to drink baby dolphin blood, and that's why my eyes are hazel. So anyway, Edward. He's also very graceful and stuff cause of his vampire powers, which is in direct opposition to Bella, cause she's really awkward. She's also incredibly clumsy.
Oh yeah, bad vampires have red eyes. It's not really important, but that's okay, it is because Edward and Bella are TOTALLY IN LOVE so shut up.
Anyway, so Edward saves Bella from a car that almost squashes her. Then Bella goes to Port Angeles with her friends, and she gets all lost looking for a book store (Bella is really smart, so she needs new books because she's, like...way smart and stuff and she's so DARN CUTE with her awkward clumsiness) and so since she's so freakin' pretty, some guys are all "AAH HEY WE'RE GONNA RAPE YOU!" except they never say that, but it's implied, although it could just be that they need directions to Walmart or the pet store.
So yeah, Edward shows up in his shiny Volvo, and he's really mad about those guys because HE CAN READ THEIR THOUGHTS. Which is cool, and also totally makes sense. But he can't read Bella's thoughts. Because that also makes sense.
So they go to this restaurant and Bella eats and there's a hot waitress and also something with ravioli. I didn't really pay attention at this part. But I think Edward didn't even care about the hot waitress, because that darn Bella is so endearing with her clumsiness. SHE'S AWKWARD. They talk about how Edward is a vampire, and he's all "Bleh! I'm a monster!" and Bella's all "whatever, dude" so that's good because Bella is just SO DANG unique, and because of that she isn't scared.
Then some stuff happens, there's baseball and thunder, because vampires like to play in thunderstorms or whatever. Also, Rosalie doesn't like Bella. Bella also acts clumsy and awkward, and all the boys think it's way hot. And that's about all that goes down, except that Edward and Bella fall mad-hot in love and they stare at each other in the eyes in a magical meadow. So yeah this part was really boring, and it talked a lot about innocence. And lambs. For some reason.
Then they're playing baseball, and these three bad vampires (you can tell because they have red eyes. Told you it was important) they show up and James is all "I'm totes gonna eat Bella!" and everyone's scared and stuff, because delicate Bella is really clumsy and can't defend herself. Then James beats Bella up in a dance studio, and bites her, but it's okay cause he dies, except we don't get to see him die, we just get to listen to Bella complain about being in pain and I'm all "BELLA you're so selfish and awkward! Why are you so clumsy? Why don't you pay more attention to the cool parts, like vampire dismemberment and death?!" So Edward, who is, like, crack-addicted to Bella's blood, somehow sucks all the venom out of her blood and doesn't kill her. Somehow. I'm sure there's an explanation for why that makes sense. ...Look, he's hot!
So Bella goes to the hospital, and then she goes to prom, and she's really awkward and clumsy. Did I mention that she's awkward and clumsy? It's really cute and endearing.
Bella wants to turn into a vampire at prom because she's an idiot and is all "YEAH MAKE ME HOT AND SPARKLY AND HAVE UNICORN-GOLD EYES!" and she's 17, so she's kind of predisposed to be an idiot. But since she's so vulnerable and cute, it's okay.
And that's the gist of Twilight. It is very romantic and action packed, if you like the sort of action that involves driving kind of fast and talking about innocence. And who doesn't?