Seventeen-year-old Bella Swan leaves Phoenix, Arizona and moves to Forks, a small town located on Washington state's Olympic Peninsula, to live with her father, Charlie, the town's police chief. Her mother, Renée, is remarried to Phil, a minor league baseball player.
Bella becomes re-acquainted with Jacob Black, a Native American teen who lives with his father, Billy on the Quileute Indian Reservation near Forks. At school, she finds the mysterious and aloof Cullen siblings particularly intriguing. She is seated next to Edward Cullen in biology class, but he seems repulsed by her.
When Bella is nearly struck by a van in the school parking lot, Edward instantaneously covers a distance of over thirty feet to put himself between her and the van, stopping it with only his hand. He refuses to explain his actions to her, warning her against befriending him. Jacob tells Bella about a long-standing animosity between the Cullens and the Quileutes; the Cullens are not allowed on the reservation.
When Edward saves Bella again, this time from a gang, after research she concludes that he is a vampire. He eventually confirms this, explaining that he found her scent irresistible back in biology class and that the Cullens only consume animal blood.
The pair fall in love and he introduces her to his vampire family. Carlisle Cullen, the patriarch, is a doctor at the Forks Hospital. Esme is his wife, and Alice, Jasper, Emmett and Rosalie are their informally-adopted children. The family's reaction to Bella is mixed, as some of the Cullens are concerned that the family's secret could be exposed.
Edward and Bella's relationship is jeopardized when three nomadic vampires—James, Victoria, and Laurent—arrive, responsible for a series of deaths being investigated as animal attacks. James, a tracker vampire, is excited by Bella's scent and becomes obsessed with hunting her for sport. The Cullens protect Bella from the trio. Laurent chose to warn the Cullens about James, who in turn attempt to draw James away from Bella, but James manages to track her to Phoenix. She is there hiding with Jasper and Alice, and James tricks her into thinking he kidnapped her mother by luring her into her old ballet studio.
James revealed the kidnapping was a ruse as he attacks Bella, infecting her with vampire venom. The Cullens arrive and kill James, decapitating and burning him, as Edward removes the venom from Bella's wrist, preventing her from becoming a vampire.
In the aftermath, Edward accompanies an injured Bella to prom, where he refuses her request to transform her into a vampire. They are unaware that James' mate, Victoria, is watching them, plotting revenge for her lover's death.