Stephenie Meyer has stated that the apple on the cover represents the forbidden fruit from the book of Genesis. It symbolizes Bella and Edward's love, which is forbidden, similar to the fruit of the Tree of Knowledge of Good and Evil, as is implied by the quote from Genesis 2:17 that is quoted in the beginning of the book. It also represents Bella's knowledge of what good and evil are, and the choice that she has in partaking of the "forbidden fruit", Edward, or choosing not to see him.
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. Bella attracts much attention at her new school 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 class on her first day of school, Edward seems utterly repulsed by her. After tricking a family friend, Jacob Black, into telling her local tribal legends, Bella concludes that Edward and his family are vampires who drink the blood of animals, not humans. Edward reveals that he initially avoided Bella because the scent of her blood was so desirable to him. Over time, Edward and Bella fall in love.
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 that Bella must give herself up to save her. She does so and James attacks her, but Edward, along with the rest of the Cullen family, rescues Bella before James can kill her. Once they realize that James has 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.