"Pretty Little Liars" follows four estranged best friends who are reunited a year after the leader of their clique goes missing, only to realize that they're all receiving anonymous messages from someone who knows all their secrets.
Either these shows spun from great books (many of which I read first!) or are based on well-known literary works, often with a modern spin. I exclude gothic novels and comics from this list since I have a list for that lol.