Arkham City

Batman: Arkham City takes place entirely in the new incarnation of Arkham Asylum, Arkham City. After the Joker's takeover of the asylum which was thwarted by Batman, Warden Quincy Sharp took full credit for the Joker's defeat and was quickly elected as Mayor of Gotham City. Manipulated by Professor Hugo Strange into creating Arkham City, Sharp walls off and isolates a large part of Gotham, turning it into the new form of Arkham Asylum. Sharp leaves Professor Strange in charge as chief administrator with security handled by the militarised TYGER troops. Bruce Wayne openly protests against the city's creation and is swiftly apprehended by TYGER and becomes an inmate. However, Bruce escapes the vengeful inmates and becomes Batman to investigate Strange's mysterious Protocol 10.

History
The concept of Arkham City was established long before the Joker's takeover of the asylum, conceived by Strange and his secret master Ra's al Ghul, and expanded on by Warden Sharp. During the Joker's takeover, Batman may find a hidden room in Sharp's office, revealing a large blueprint map of the city.

After Sharp takes credit for the liberation of the asylum, he was quickly elected as Mayor of Gotham and executed to the construction of Arkham City. Numerous people were involved in the new Arkham's creation but by the time it was finished, most if not all of those involved were double-crossed by Strange and imprisoned within the city walls to cover up his tracks, these innocent people becoming known as "political prisoners". Sharp, paranoid to end crime in Gotham, labelled everyone and anyone who even had the slightest criminal record to be inmates of Arkham City and imprisoned without trial or the rite to objections. Strange furthered this by imprisoning anyone trying to investigate or speak out against Arkham as political prisoners.

Bruce Wayne is among those who are unlawfully imprisoned in Arkham, but he obtains his Batsuit to explore the city and discover the secret of Protocol 10. He is eventually poisoned with the Joker's Titan-infected blood and reunites with Ra's al Ghul to create an antidote with help from Mr. Freeze. Batman eventually confronts Strange in his base operations, the Wonder Tower, where Strange initiates Protocol 10, revealed to be a mass bombing of the city by TYGER to wipe out the criminals, the true goal of Ra's al Ghul. Ra's mortally wounds Strange after he has fulfilled his purpose, but Strange activates Protocol 11 which destroys the Wonder Tower in the event of his defeat. Batman and Ra's fall from the tower, but Ra's attempt to kill Batman fails and results in his own apparent death.

Batman confronts the Joker who teamed up with Talia al Ghul to obtain the antidote from Batman, but the Joker kills Talia and reveals he has been working with Clayface to shadow his moves. Batman kills Clayface and his struggle with the Joker results in the antidote's destruction, the Joker dying shortly after. Batman exits Arkham Cty with the Joker's body as Commissioner Gordon and Gotham PD arrive outside. While the fate of Arkham remains unknown, it is implied to still be in operation after the Joker's death.