Bella is preparing for her wedding. During the reception, Jacob returns after hearing about Bella and Edward’s engagement. While dancing with him in the woods, away from everyone else, Bella admits that she and Edward plan to consummate their marriage on their honeymoon while she’s still human. Jacob becomes furious, knowing that Edward could easily kill Bella. Sam and the others restrain him and angrily leave.
After the wedding, the couple spends their honeymoon on Isle Esme and they make love for the first time. The next morning, Edward realizes that Bella has numerous bruises and is upset at himself for hurting her, though Bella insists she enjoyed the experience. Edward swears not to make love again until she becomes a vampire. Two weeks after their honeymoon, Bella realizes that she is pregnant with a half-mortal, half-immortal child. Edward is terrified by the news, knowing that she may not survive the pregnancy. He says that Carlisle will remove the baby. She refuses, as she wants to keep the baby and convinces Edward’s sister, Rosalie, who has always wanted a child, to help protect her baby. They fly back home to Forks, Washington. She has only been pregnant for two weeks, but the baby is growing very fast.
Jacob rushes over to the Cullen’s house and finds Bella already heavily pregnant. He becomes upset, saying that they should remove it as soon as possible. Bella says that it is her choice. As she gets bigger, the quality of her health declines then rapidly improves as she starts drinking human blood to satisfy the baby’s vampiric thirst for blood. Edward comes to love the baby as much as Bella does as he reads it thoughts, learning that his child loves Bella in return and doesn’t want to hurt her.
Soon after, Bella drops a cup of blood and as she bends down to pick it up, the baby breaks her back. She nearly dies giving birth. To save her life, Edward injects Bella’s heart with his venom to transform her into a vampire, but nothing seems to happen and Bella is presumed dead. Greatly distraught, Jacob attempts to kill the baby, but stops when he realizes he has imprinted on the baby.
When the werewolves learn of Bella’s death, they attack the Cullens’ house in an attempt to kill the baby as they fear it would become a threat. Edward, Alice, and Jasper defend their home and their family, and are later helped by Carlisle, Esme, and Emmett. Jacob then runs outside to stop the fight and shapeshifts. Jacob and Sam shortly communicate with each other telapathically. Edward reads Jacob’s mind and announces that Jacob has imprinted on Renesmee and since it is the wolves’ law not to harm anyone who has been imprinted on, they are forced to retreat. After Bella is cleaned and dressed, her cuts from her difficult labor heal as the venom spreads through her body. The last scene shows Bella open her red eyes as a newborn vampire.
In a post-credits scene, Aro and his brothers Marcus and Caius received a letter from Carlisle.