The story is set primarily in the small town of Forks in northwest Washington State, as well as nearby communities such as La Push and Port Angeles. The very beginning and the climax take place in Phoenix, Arizona.
Isabella "Bella" Swan The narrator of the story, a human girl who moves from Phoenix, Arizona to Forks, Washington to live with her father.
Renee Dwyer The mother of Isabella, who lives in Phoenix, Arizona and recently married a minor league athlete.
Charlie Swan The father of Isabella and Police Chief of Forks, Washington.
Billy Black A Quileute Native American tribal elder who sells his truck to Charlie Swan, which becomes a gift to Bella.
Edward Cullen A vampire in the Cullen family who possesses the ability to read most minds, but not Bella's. He is attracted to Bella in a predatory manner, but also falls in love with her.
Emmett Cullen A vampire in the Cullen family who possess unusual strength.
Alice Cullen A vampire in the Cullen family who takes a strong liking to Bella and possesses precognitive powers.
Rosalie Hale A vampire in the Cullen family who takes a strong dislike to Bella and is Emmett's mate.
Jasper Hale A vampire in the Cullen family who possesses the ability to influence people's emotions.
Carlisle Cullen The adoptive father of the Cullen and Hale children.
Esme Cullen The wife of Dr. Cullen, adoptive mother of the Cullen and Hale children.
Jacob Black The fifteen-year-old son of Billy Black, who tells Bella about the Quileute legends about werewolves and vampires.
James A vampire who visits the Cullens and hunts down Bella.
Victoria A vampire who visits the Cullens and works with James.
Laurent A vampire who visits the Cullens with James and Victoria.
Phil Dwyer The new husband of Renee, a minor league baseball player.
Ms. Cope Forks High School Receptionist who gives Bella her class information on the first day.
Mr. Mason Bella's English teacher.
Jefferson Bella's Government teacher.
Eric Yorkie Befriends Bella and becomes romantically interested in her.
Mr. Varner Bella's Trigonometry teacher.
Jessica Stanley Befriends Bella and is romantically interested in Mike.
Angela Weber A silent and shy girl who befriends Bella.
Isabella "Bella" Swan moves from Phoenix, Arizona to Forks, Washington to live with her father Charlie. While unhappy with this decision, it is one she makes on her own as she wants to give her mother Renee the chance to follow her new husband Phil, a minor league baseball player, to Florida. Bella adjusts well to her new high school in Forks, but notices the five Cullen siblings: Edward, Emmett, Alice, Jasper Hale, and Rosalie Hale. They are all adopted by the young doctor Carlisle Cullen and his wife Esme, are unbelievably beautiful, and tend to keep to themselves. Bella is shocked when she finds that she has to share her Biology class table with Edward, and even more surprised when it seems that Edward takes an instant dislike for Bella without even speaking to her. Edward disappears from school for several days and when he returns tries to be friendly with Bella, which confuses her. The next morning, she is almost run over by a van and only saved by the unnatural strength and speed of Edward, who swoops in to rescue her from sure death. He asks her to keep quiet about what she had witnessed about him, and she abides by his request. She tries to be friendly with Edward in the aftermath, but he does not acknowledge her existence for the next six weeks.
As the girls' choice dance approaches, Bella is asked by several boys to take them to the event. She refuses them all, but Edward starts speaking to her again, asking if she would go with him to Seattle instead, which was the excuse she gave for not attending the dance. Edward starts to show unusual attention to Bella, which others notice. However, he does not go with Bella when she invites him to come along to a beach outing planned by Mike Newton, one of the boys who's interested in her. She goes on this outing to La Push and meets the Quileute Native American teen Jacob Black - Jacob's father Billy Black sold Charlie the truck that he gave to Bella as a gift. Through Jacob, she finds out that the Cullens are "cold ones" - vampires - and struck a peace agreement many years ago with the Quileute, who legend states possess werewolves among their number.
A few days later, Bella goes to Port Angeles with two of her friends, who want to go dress shopping for the dance. Alone, Bella is trapped by four men, but is saved by Edward in his car. They wind up having dinner together and begin to discuss what exactly he is. They take turns asking each other questions: Bella interrogates Edward on being a vampire, on his abilities, and his family; Edward interrogates Bella about the details of her own life and personal history. Edward convinces Bella not to go Seattle on the day of the dance, as he has other plans for her. However, complications arrive one evening when Billy Black sees Edward and Bella together, and he unsuccessfully tries to convince Bella to stay away from the vampire.
On the morning of the dance, Edward instead takes Bella on a long hike and she sees why vampires avoid sunlight: their skin glistens diamond-like when exposed directly to the sun. The two admit their love to each other during this idyll. The following morning, Edward takes Bella to meet his family at their home and tells the story of how Carlisle became a vampire and assembled the Cullen family as they now stand. That evening, Edward takes Bella to watch a baseball game played by his family, which due to their strength and speed must be hidden by a thunderstorm. The game attracts a pack of nomad vampires, however, and one of those vampires is a tracker names James. James decides to hunt Bella after discovering she is a human, but the Cullens protect her: Alice and Jasper take Bella back to Phoenix, Arizona to hide, while Edward, Emmett, and Carlisle try to chase James and ambush him. However, James flees to Phoenix and tricks Bella into thinking he's holding her mother hostage. She goes to James willingly only to find her mother is not with him; further, James plans to record his killing of Bella so that Edward would try to avenge her. Bella is attacked by James but saved by the Cullens: Edward pulls James off Bella, Emmett and Jasper kill James, while Carlisle and Alice care for Bella's broken body. They discover Bella was bitten by James, and Edward sucks out the venom so that she won't become a vampire.
Bella survives and is hospitalized, and a cover story is fabricated to hide the truth of what happened. Edward stays with Bella while she recovers at the hospital and Bella asks why he didn't let the venom change her into a vampire. He refuses to do so, as she doesn't want her to become a monster. She finds out that Alice, who has precognition, had a vision where Bella becomes a vampire; however, Edward points out that she also saw Bella die and that didn't come true. Bella and Edward repeatedly profess their love for each other, but Bella still wants to be transformed so she can be with Edward forever. Weeks later, back in Forks, Bella is surprised when Edward takes her to the prom; Jacob Black is also in attendance, with a message that his father still wants her to break up with Edward and that they'll be watching. Bella confesses to Edward that she was hoping he would turn her into a vampire this evening but he continues to refuse. For the time being, their love for each other is enough.