Not much is known about the narrative for the upcoming Batman: Arkham Knight. Rocksteady has been very hush hush, but I do expect a full stage demo during E3.
It isn’t much, but a new series just dropped that will give you an insider look on the series. According to the description box of the official Arkham Knight Youtube page “In the episode, we give you the low down on the new Dual Play gameplay feature, shed more light the narrative elements at play in Batman’s relationship with his allies, and bring you inside the studio as we celebrate another milestone in the development of Batman: Arkham Knight.”
I personally enjoyed it and it’s the best place to get a inside look on the game. Check it out below! Batman: Arkham Knight drops June 23rd for PC, X1 and PS4.