Breaking Dawn is split into three separate "books," or parts. The first part details Bella's marriage and honeymoon with Edward, which they spend on a private island off the coast of Brazil. Edward grants Bella's wish and makes love to her. Soon after, Bella sees a box of unused tampons and realizes that she is pregnant. After contacting Carlisle, who confirms her belief, she and Edward plan to return home. Edward, concerned for her well being, urges her to get an abortion. However, Bella wants to keep the child and decides to contact Rosalie for support, knowing that Rosalie has always wanted children.
The second part of the novel is written from Jacob Black's point of view, and lasts throughout Bella's pregnancy and childbirth. The pack of werewolves, not knowing what danger the unborn child may pose, make plans to destroy it, even though they must kill Bella to do so. Jacob vehemently disagrees with this decision and revolts, leaving the pack to form his own with Seth and Leah Clearwater. Bella soon gives birth, approximately a month after becoming pregnant. The baby breaks many of her bones, and Bella loses massive amounts of blood. In order to save her life, Edward changes her into a vampire. Jacob, who was present for the birth, immediately "imprints" — an involuntary response in which a werewolf finds his soul mate — on Edward and Bella's newborn daughter, Renesmee.
The third section of Breaking Dawn shifts back to Bella's perspective, finding her changed into a vampire and enjoying her new life and abilities. However, the vampire Irina misidentifies Renesmee as an "immortal child", a child who has been turned into a vampire. The creation and protection of "immortal children" was previously outlawed by the Volturi. After Irina presents her allegation to the Volturi, they plan to destroy Renesmee and the Cullens. In an attempt to save her, the Cullens gather vampires from around the world to stand as witnesses and prove to the Volturi that Renesmee is not an immortal child. Upon confronting the gathered Cullen allies and witnesses, the Volturi discover that they have been misinformed and immediately execute Irina for her mistake. However, they remain undecided on whether Renesmee should be viewed as a threat to the secret existence of vampires. At that time, Alice and Jasper, who had left prior to the confrontation, return with Nahuel, a 150-year-old vampire-human crossbreed like Renesmee. He demonstrates that the crossbreeds pose no threat and the Volturi leave, knowing that they no longer have just reason to destroy Renesmee. Bella, Edward and Renesmee return to their home, free to live their lives in peace.