"I'm Back Bitches And I Know Everything -A"
-A is a person who is texting the girls and is trying to hurt them as much as possible.
The First -A was Hanna Marin's Best friend Mona Vanderwall the Second -A was Alison's twin sister Courtney but they Later found out that that the Alison they knew was actully Courtney and she was crazy and the Courtney they knew was Alison.