Isabella "Bella" Swan moves from sunny Phoenix, Arizona to rainy Forks, Washington to live with her father, Charlie. She chooses to do this so that her mother, Renée, can travel with her new husband, Phil Dwyer, who is a minor league baseball player. Even though Bella never had many friends in Phoenix, she attracts much attention at her new school in Forks, and is quickly befriended by several students. Much to her dismay, several boys in the school compete for shy Bella's attention.

When Bella sits next to Edward Cullen in biology class on her first day of school, Edward seems utterly repulsed by her. He even attempts to change his schedule to avoid her, leaving Bella completely puzzled about his attitude towards her. After tricking a family friend, Jacob Black of the Quileute tribe, into telling her the local tribal legends, Bella concludes that Edward and his family are vampires. Although she was inexplicably attracted to him even when she thought Edward drank human blood, she is much relieved to learn that the Cullens choose to abstain from drinking human blood, and drink animal blood instead. Over time, Edward and Bella fall in love. Their foremost problem is that to Edward, Bella's scent is a hundred times more potent than any other human's, making Edward struggle to resist his desire to kill her. However, despite this they manage to stay together safely for a time.

The seemingly perfect state of their relationship is thrown into chaos when another vampire coven sweeps into Forks and James, a tracker vampire, decides that he wants to hunt Bella for sport. The Cullens plan to distract the tracker by splitting up Bella and Edward, and Bella is sent to hide in a hotel in Phoenix. Bella then gets a phone call from James in which he says that he has her mother, and Bella is forced to give herself up to James at her old dance studio, where he attacks her. Edward, along with the rest of the Cullen family, rescue Bella before James can kill her. Once they realize that James had bitten Bella's hand, Edward sucks the venom out of her system before it can spread and change her into a vampire. Upon returning to Forks, Bella and Edward attend their prom and Bella expresses her desire to become a vampire, which Edward refuses to let happen.