This often refers to the " Knightquest " chapter of the saga. In this part, Jean-Paul Valley (Azrael) takes over the mantle of Batman while Bruce Wayne recovers from his broken back.
" Knightfall " is a legendary DC Comics storyline where the villain Bane "breaks the bat." If you are looking for volume or issue "2x1": Knightfall 2x1
You can find these storylines in trades such as Batman: Knightfall Vol. 2: Knightquest . 3. Star Wars: Knightfall (Operation Knightfall) This often refers to the " Knightquest " chapter of the saga