Spoiler warning! This article contains plot details about an upcoming episode.
In Batman: Arkham City, Bruce Wayne is captured by Hugo Strange the conductor of Arkham City. He announces to Bruce Wayne that Protocol 10 will begin and if he tries to stop him everybody will know his secret. As Bruce Wayne escapes he alerts Alfred to deliver his Batsuit on top of the ACE CHEMICALS Building. As he gets his Batsuit Batman notices that Catwoman is about to be exucuted in front of Two-Face. Batman stops the exucution and while he is talking to Catwoman about Protocol 10, Joker shoots a sniper at Catwoman. Batman pushes Catwoman to miss the sniper and Batman finds out that Joker is in the church. Batman gets to the church and Joker sends a signal bomb. Batman jumps out of the church and tracks Joker in the Steel Mill. Joker catches Batman and poisons him with his diaseased blood. Joker tells Batman that Mr. Freeze has the cure and Batman goes to the GCPD building to get it from him. Batman finds out that Mr.Freeze was taken by Penguin in the musuem so he goes and finds him. Batman rescues Mr. Freeze after a fight with Solomon Grundy but Mr. Freeze says that he will need Ra's Al Ghul's blood. In order to get Ra's Al Ghul's blood he must do the Demon Trails which only one man has survived from. After Batman completes it he fights Ra's Al Ghul and gets his blood and delivers it to Mr. Freeze. Mr. Freeze says he must find Nora, Freeze's wife. Batman says that he needs the cure now and Mr. Freeze disagrees. He crushes the cure's vial in his hands and trys to defeat Batman using his Freeze Gun. Batman defeats Mr. Freeze and finds out that the cure was stolen by Joker who is now cured. Batman escapes the GCPD building only to find out that Vicki Vale a Gotham City news anchor helicopter was shot by Joker's snipers. Batman rescues Vicki Vale and gets to the Steel Mill only to find out that Joker still has the cure. Batman fights Joker and other enimies including Mr. Hammer and defeats Joker. A part of the collapsed roof from the Steel Mill falls onto Batman and Talia Al Ghul grants Joker immortality if he does not kill Batman. Batman is rescued by Catwoman who tells him that Protocol 10 is starting. TYGER forces are shooting Arkham City and Batman breaches Wonder Tower, the tower that Hugo Strange is in. Ra's Al Ghul stabs Hugo Strange while he is talking about Protocol 10 telling him that he did not follow his orders. Batman finds out that Ra's Al Ghul has gone crazy do to immortality. Hugo Strange activates a Wonder Tower explosion and Batman and Ra's Al Ghul escape just in the nick of time. Batman stabs Ra's Al Ghul in midair and finds out that Joker has taken captive of Talia Al Ghul in the old cinema. Batman sees Talia Al Ghul stab Joker only to find out that it is not Joker just Clayface. While Clayface is forming the real Joker shoots Talia Al Ghul killing her. Batman retrives the cure form Clayface Joker jumps on him. Batman drops the cure vial breaking it and Joker dies because he did not get the cure in time. Batman carries Jokers dead corpse out of the old cinema.
Batman: Arkham City consists of a fight and counter mechanic and the ability to use gadgets. The gadgets include Line Launcer, Remote Electrical Charge, Explosive Gel, Batclaw, Sonic Batarang, etc. Batman also has the ability to upgrade his power and gadgets.