The story opens with the revelation that Seattle, Washington is being plagued by a string of unsolved murders, which Edward suspects is caused by a new vampire that is unable to control its thirst for human blood. As Edward and Bella apply to colleges, Bella explains to Edward her desire to see her friend, Jacob Black, a werewolf. Although Edward fears for her safety, Bella insists that neither Jacob nor his wolf pack would ever harm her, and she begins visiting him occasionally. Meanwhile, Alice Cullen has a vision that Victoria, a vampire who is hunting Bella for revenge, has returned to Forks. A few days later, Edward proposes to Bella and, despite harboring an aversion to marriage, she accepts.
Bella and the Cullens soon realize that the Seattle murders are being committed by an "army" of newborn vampires, controlled by Victoria. The Cullens join forces with the wolf pack to combat this threat. As everyone else prepares for battle, Edward, Bella, and Jacob camp in the mountains, hidden during the battle, where they are later joined by Seth Clearwater, a young wolf pack member, to wait out the fight.
In the morning, Jacob becomes upset when he overhears Edward and Bella discussing their engagement and threatens to join the fight and get himself killed. To stop him, Bella kisses Jacob and comes to realize that she is in love with him as well. During the battle, Victoria tracks Edward's scent to Bella's forest hiding place, and Edward is forced to fight. After Victoria and her army are successfully destroyed, Bella explains to Jacob that while she loves him, her love for Edward is greater. After receiving a wedding invitation from Edward, Jacob runs away in his wolf form to escape his pain, angry and heartbroken at Bella's decision to become a vampire.