The PowerBook by Jeanette Winterson

Winterson enfolds her seventh novel within the world of computers, and transforms the signal development of our time into a wholly human medium. The story is simple: an e-mail writer called Ali will compose anything you like, on order, provided you're prepared to enter the story as yourself and risk leaving it as someone else. You can be the hero of your own life. You can have freedom just for one night. But there is a price, and Ali discovers that she, too, will have to pay it.

The PowerBook reinvents itself as it travels from London to Paris, Capri, and Cyberspace, using fairy tales, contemporary myths, and popular culture to weave a story of failed but requited love.