Lain is a quiet girl who doesn't know much about computers. Till she connects to the wired and gets a mail from a girl. A girl who committed suicide a while ago. While the connection with the wired is getting stronger worlds starting to fade and nothing is what it seemed to be.
The show has a exceptionally good plot which unfolds in the most unexpected ways. Included is a lot of philosophy, a little science and a reasonable link to the reality.
The anime itself is kept quiet and slow with a lot of still images so your attention is mostly going to the conversations and other strange sounds. That doesn’t mean the anime isn’t worth watching, it’s beautiful drawn with eye for detail.
Definitely worth a 9, although I’m not going to shout “bring it back!”. The show has 13 episodes and a satisfying ending. If they made more, it wouldn’t be Lain anymore.