Wow. This is a brilliant - and underrated - show!
I decided to give Pretty Little Liars a chance and watched some episodes online, not knowing anything about it and I am so glad I did! Don't let the fact that it centers around 4 teenage girls put you off, it's in the same classy, intelligent genre as desperate housewives (in its hey day).
The show focuses on four friends - Aria, Spencer, Hanna and Emily - who start receiving text messages (and other kinds of messages) from a mysterious figure known only as "A". "A" seems to know all of the girls' secrets, including the fact that their best friend - and self-proclaimed leader of their posse - Alison was murdered the year before. Alison of course is not who she seemed to be, and the girls discover more and more about who she really was as they try to uncover her murderer (and "A"'s identity).
This show is brilliantly written (far better than the books it is based on), enjoyable and mature at the same time. All of the main girls have their own demons - Spencer is constantly trying to live up to her parent's expectations; Aria is having an affair with an older man; Hanna suffers from an eating disorder; Emily is struggling with her sexuality - but the characters are much more than just that. The casting overall is brilliant, even the supporting actors (the parents, schoolmates, teachers) do a wonderful job.
It's a real shame the show was only shown on smaller television networks, and didn't generate much of a following here in the UK.
This show is well worth a try. You won't be disappointed!