Maxie Zeus is still running things from inside Arkham Asylum, and his mad assistant is up to something, leaving the Dark Knight to stop her.
Maxie Zeus sent a message to his gang via his girlfriend, Iris. She overheard them discussing their leader in a bad light, but she told them to call off their heist anyway. Iris had a breakdown and became Harpy. She was there to take down the gang when they went on with plans. They escaped when Batman showed up and Harpy went for him instead.