Bella Swan lived in Phoenix, Arizona with her mother Renée and step-father Phil, who is a minor-league baseball player. Phil gets transferred to play baseball in Florida, so they decide to move there but Bella decides to move in with her father, Charlie; who is the chief of police in Forks, Washington. Bella moves to Forks and is greeted by Charlie's friend, Billy Black, and Billy's son, Bella's childhood friend, Jacob Black. Charlie purchases a truck from Billy as a homecoming gift for Bella.
Bella meets the students at Forks High School on her first day, including Mike Newton, Eric Yorkie, Jessica Stanley, Tyler Crowley and Angela Weber. At the cafeteria, Bella learns about the strange Cullen family, five teenage-adult foster kids adopted by Carlisle, a young doctor in the community; who is 23 years old and married to Esme.
In Biology, Edward, one of the Cullen "kids”, seems completely disgusted with Bella and he goes away one second before the bell rings. She yearns to confront Edward but he is absent for a week. When he returns, he seems friendly and kind towards her, explaining that he was gone for "personal reasons". Much to Bella's surprise, Edward's black eyes have turned golden brown.
At the parking lot, Tyler's van goes out of control and is about to crush Bella. Edward, who is standing by his car, across the lot, far away from Bella, moves quickly and stops the van with his hand, leaving a huge dent in the van's door and a small dent at the end of Bella's truck. Bella is the only one who sees this.
Bella tries to get Edward to tell her how he stopped the van, but he warns her against befriending him, and that he might be a bad guy. The next day, their class goes on a field trip where she declines Mike's invitation to prom, and Edward relentlessly dodges her questions but asks his own.
Bella and her friends go to the La Push beach and Jacob arrives with two of his friends, Embry Call and Sam Uley. She persuades him to tell her a tribal story involving the Cullens.
As Bella goes with Angela and Jessica to Port Angeles to shop for prom dresses, Bella goes off by herself to find a book on Quileute legends. Soonafter that, she runs into a dangerous gang about to make their move on her before Edward unexpectedly appears to stop them. Edward and Bella later have a deep conversation regarding his ability to hear people's thoughts and his inability to read her mind, confessing it as "very frustrating". In the meantime, a close friend of Charlie's is found dead in his boat.
Bella uses her book and finds a website about vampires when searching 'The Cold One' on Google. The website shows details about vampires and the descriptions she reads matches Edward's characteristics. Upon realizing what he is, she confronts him the next day in a clearing in the woods nearby. Instead of being scared of the truth, she just bravely accepts him for what he is: a vampire.
Edward and Bella fall in love and openly show their relationship. Eventually, he introduces her to his vampire family: Carlisle, Esme, Alice, Jasper, Emmett and Rosalie. Soon, the pair realize their love for each other is so strong and he hopes to never lose control when he is around her.
Later on, Bella is offered a chance a human rarely or never gets: to assist a baseball game between vampires. The game goes apparently well, until Alice sees a vision of three nomadic vampires that have been involved in the killings in Forks lately approaching. Edward and Bella prepare to leave, but it's too late. James, a tracker vampire, is intrigued by Edward's protectiveness over a human and wants to hunt Bella for sport. Carlisle tells James, Laurent, and Victoria to leave after James' outburst. However, he wants to kill Bella, and plots a plan to get rid of the Cullens and eat her. Knowing about the plan, the Cullens split up Edward and Bella to save her life. Edward, Emmett, and Rosalie find out James has figured out the truth and has escaped. Esme and Rosalie stay behind to protect Charlie while Edward, Emmett, and Carlisle go to Phoenix where Bella is hiding in a hotel with Alice and Jasper.
James calls and lies to Bella that he has caught her mother and will kill her if Bella doesn't come to a ballet studio alone. Alice, who can see the future, gets to know something terrible will happen in a dark ballet studio. When Jasper and Alice are in the hotel lobby, Bella ditches them and takes a taxi and goes to the studio, where she gets bitten by James on the wrist while he is fighting Edward.
James is burned to ashes by Emmett, Jasper and Alice, and Edward sucks the venom out of Bella's system, which stops her transformation. She awakes in the hospital and recovers with her mother by her side. Edward tells her to move to Jacksonville so she would be safe from him, but she persuades him otherwise.
In the end, Edward and Bella attend their high school prom and she asks him to turn her into a vampire to be with him forever, but he kisses her instead. Bella decides to enjoy the evening, but is determined to someday become a vampire to be with him.
Victoria, secretly watches the pair dance and swears revenge.
