The Joker allows himself to be caught and brought to Arkham Asylum, where his plan unfolds immediately: Harley Quinn seizes control of the facility's security systems, freeing him alongside a wing full of his gang transferred in from Blackgate. Batman is locked out of any outside help by bomb threats across Gotham and works alone — tracking Quinn to rescue Commissioner Gordon, surviving the Scarecrow's fear toxin, fighting Titan-fueled Bane, and working systematically through each wing of the asylum. A secret Batcave installation on the island lets him restock between confrontations.