It is announced that a DLC story starring Batgirl will be joining the game Batman: Arkham Knight. The story takes place before Arkham Asylum where Commissioner Gordon is held captive by the Joker and Harley Quinn at the Seagate Amusement Park. With the help of Robin, Batgirl will learn everything she learned from Batman to save her father. The DLC was made by Arkham Origins developer WB Games Montreal, not series creator Rocksteady.
The trailer is here at IGN