On the plane to Italy, Alice explains to Bella that the Volturi are the only other big vampire family besides the Cullens in the world. Only the Volturi are way more powerful. In fact, they preside over a whole contingent of vampire minions who guard their city and possess special gifts that make Alice and Edward’s abilities look "like a parlor trick" (19.36).
Bella still can’t understand why Edward would kill himself. Yes, he once said he couldn’t live without her. But when he broke up with her, he didn’t seem to care about her fate. She realizes that, even if she saves Edward, it doesn’t mean he’d want her back, but "This was the price I would have to pay to save his life. I would pay it" (19.75).
Bella says that she wishes Alice could have been right about her vision of Bella becoming a vampire. Alice admits she’s been debating whether she should just change Bella herself. Bella's answer? "Bite me!" (19.116).
During the plane ride, Alice keeps having visions: the Volturi reject Edward’s request to be killed. They want him to join them and to use his mind-reading skills for their benefit. Alice learns that Edward plans to step out into the sun at noon, on the main plaza in Volterra. This will expose Edward as a vampire and force them to do away with him.
In Rome, Alice steals a Porsche Turbo and they race to Volterra. On the way, she tells Bella that, funny enough, it’s St. Marcus day in Volterra – a celebration of the legendary Christian missionary St. Marcus, who allegedly drove all vampires out of the city.