The first episode opens with the mysterious suicide of a high-school girl, Chisa Yomoda. Chisa-chan was a classmate of Lain Iwakura, a quiet, 14-year-old high-school girl. One of the other girls in the class has been receiving e-mail messages from Chisa-chan, and Lain discovers she also has mail from Chisa-chan. In the mail she explains to Lain that she just abandoned her flesh. She assures Lain that she still is alive in the 'wired' world. After getting a new 'navi' and adding a 'psyche' circuit, Lain spends more and more time in the wired. It seems that Lain has at least 2 personalities, and Lain's first personality is changing even now. Who is Lain? Who are the 'knights'? Can the wired influence the real world with a prophecy? Is the real world nothing but a hologram of the information in the wired?

Source (AniDB)