Don't read this if you plan on reading the book and don't want to know what's going to happen.
Here's the Cliff Notes version of the book, because frankly, it's to long of a book, so I'll save you some time.
It starts out with Bella having a little teenage crisis because she turns 18. I can't call it a midlife crisis, because she's only 18. She has a nightmare where she sees herself as a little old lady and Edward is with her, but since he's a vampire, he doesn't age. So she gets all freaked out, because why would a vampire want to be with a granny.
Edward and his family throw her a birthday party, which she is not happy about, because she's moody and doesn't like to get presents. I would LOVE if someone put a new stereo in my car. She's opening presents and gets a paper cut. Think of the last time you got a paper cut. It was probably no big deal, didn't even really bleed. Well, with hers, she started to bleed like crazy, and of course she was in a room of vampires so they got hungry. One tried to attack her, but Edwards pushed her out of the way, and into a glass table, where of course she cut herself and started to bleed even more.
Fast forward, Dr. Cullen fixes her up and Edward takes her home. Soon after he stops by her place and dumps her. Saying that it's not safe for her to be around him and his family because of situations like at her bday party. Her, being all teenager-ish, gets all sad and doesn't want him to leave. Basically he tells her that he does not want her in his life. While I hate both of these characters, what he said was kind of harsh. So he leaves, and she gets all depressed and doesn't hang out with any of her friends and starts having nightmares where she wakes up screaming. I can't say that I've ever started having nightmares because a boyfriend broke up with me. Holy issues Batman, this girl needs help.
Her dad gets worried about her and she tries to convince him that she's OK, so she starts hanging out with Jacob, who makes her feel better. For whatever reason, Jacob is in love with her. I will never understand how she has two guys smitten with her. They start hanging out, and she starts doing reckless things, like riding motorcycles and jumping off cliffs, because she realized, that when she does these wild things, she can hear Edwards voice.
One day, Jacob starts to act weird. Well, she finds out that he's a werewolf. And he and his crew hunt vampires. Bella is not happy about this, because she loves vampires and wants to become one. Why the hell would you want to become a vampire? Trouble is caused when Edward's sister Alice shows up because she had a vision that Bella tried to kill herself by jumping off a cliff (into water) and wanted to check on her. They find out that Edward thought that Bella was dead, and he doesn't want to live without her (even though he broke her heart and left her) so he was planning on killing himself.
So Alice and Bella rush to Italy to stop him. Sadly, they do. Then there's some stuff with other vampires who are like higher up in the vampire world, kind of like royalty or something, I was a little confused, but from what I got out of it, it sounded like they wanted Bella to become a vampire, and if the Cullens don't turn her into one, they would kill her. Something like that.
But, the Cullens and the werewolves have a treaty that says that if a vampire bites a human, the werewolves are allowed to kill the Cullens. So, if the Cullens don't bite Bella, she'll be killed, but if they do, the werewolves will kill them. Feel free to correct me if I'm wrong about this. So, of course that causes some tension between Edward and Jacob, because they hate each other, but love. Bella and I just don't understand it.
Watch the movie, it pretty much takes the important parts out of the book. I'll still read the other books in the series, because I'm hoping that either the werewolf or the vampire kills Bella. She's annoying.