pretty little liars

who is A

pretty little liars

pretty little liars is a mystery and drama book

actors: Hanna, allie, spencer, Emily, aria,

spencer allie hanna Emily and aria are all best friends but one day allie didn't come to school and they found out that allie died that night. the next day they all get a texts from an unknown number and that she left her nickname at the bottom it said A.

who is A?