Bella (Kristen Stewart) is approaching her 18th birthday, she dreams of meeting her Grandmother in the Forest with Edward (Robert Pattinson), however she realises in the dream that it isn't her Grandmother - but in fact herself as an old woman.
On the morning of her 18th Birthday her father Charlie (Billy Burke) gives her a camera and teases her about getting gray hair (which Bella reacts strongly to).
On arriving at school, Bella discovers that Alice (Ashley Greene) has arranged an 18th Birthday Party for her at the Cullen's home, which she agrees to attend after Jasper (Jackson Rathbone) used his ability to influence her mood in a positive way.
At her birthday party, Bella notices a painting in the room of a group of individuals, one of whom appears to be Carlisle. Edward explains that they are the Volturi, the closet thing that the vampire world has to Royalty.
Bells is given a number of gifts from the Cullen family, Rosalie (Nikki Reed) gives a necklace she insists 'Alice picked out'. Emmett (Kellan Lutz) gives her an empty box, which had contained a sound system for her truck - which he had already installed. When she receives the next gift, Bella accidentally cuts herself on the paper.
In an instant, Jasper launches into a blood frenzy, trying to attach Bella. Edward throws Bella across the room into a table to try and protect her. Carlisle (Peter Facinelli) and Emmett try to hold him back, with Edward becoming involved. They manage to stop Jasper, and Carlisle take Bells (who has a bad cut from glass) into his study to stitch the wound.
Whilst he works, Carlisle tells Bella the reason that Edward is against turning her into a vampire - explaining that Edward believes it will take away her soul. Bella notices a painting in the room of a group of individuals, one of whom appears to be Carlisle. He explains that they are the Volturi, the closet thing that the vampire world has to Royalty.
Edward collects Bella and takes her home.
The next day at school, none of the Cullen children attend. When Bella returns home, she sees Edward waiting outside of her house. He asks her to take a walk with him in the woods
Edward tells Bella that the Cullen's are moving away, and that he never wants to see her again, asking her to promise not to do anything silly. Bells asks Edward not to go, but he does - after kissing her once on the forehead. She tries running after him to find him, but cannot. She falls to the ground in despair.
Charlie and a number of his colleagues and friends are looking for Bella, however she is discovered in the woods by Sam Uley (Chaske Spencer), who returns her to Charlie - under the watchful eye of Jacob Black (Taylor Lautner).
Months pass, October, November, December, January, February - as Bella sits in her room in a deep depression, which also manifests itself with horrific nightmares, which continually wake Charlie up.
One morning, before school - Charlie tells Bella that she should move back with her mother, as this has gone on 'long enough'. Bella tells Charlie that she is going on a girls shopping trip with Jessica (Anna Kendrick), which she hastily arranges after the conversation has finished
Whilst out with Jessica, she is shouted at by a gang of men on motorcycles, when she approaches them, she sees a vision of Edward telling her not to go. She does anyway, climbing on the back of one of their bikes. As they drive along, numerous visions of Edward appear to her - until she screams for the bike to stop, at which point they disappear.
Bella then reconnects with Jacob, visiting him at his house. She has bought 2 motor-cycles from a junk yard and wants him to help her repair them, which he agrees to. They spend a long time fixing-up the bikes until they are ready to be used.
Whilst out one afternoon, Bella and Jacob drive near to a cliff - where she sees some of Jacobs friends playing near the edge. They then push one of the guys over, which horrifies Bella. Jacob explains that they are Cliff Jumping, however that things with Sams gang are strange, and Jacob doesn't like the way that Sam looks at him.
Jacob and Bella decide to try the motorbikes out. When Bells starts hers, she sees a vision of Edward asking her what she is doing, which causes her to stall the bike. When she restarts it, she just takes off at speed - with visions of Edward appearing to her as she rides unsteadily along. Eventually she loses control of the bike, is flung off it into a rock - on which she cuts her head.