Bruce Wayne meets with Lucius Fox to discuss the status and business options of a crumbling Wayne Enterprises. After their discussion Lucius is curious as to why Bruce did not inquire about any new equipment (for his Batman activities), noting that their meetings used to "end with an odd request." Bruce replies that he is retired from his Batman career, but Lucius coerces him to look at some new stuff anyway " just for old times sake." They soon enter the Applied Sciences division which has still been kept secret by Fox and he then unveils a new vehicle. Bruce asks Lucius what the vehicle is called to which he replied "it has some long, uninteresting Wayne Enterprises designation", but he simply chose to dub it "The Bat". He also noted that it did indeed "come in black." (a reference to the first film). While mentioning many of its features to Bruce, Lucius notes that he had not designed a functioning auto-pilot, but that someone of Bruce's intellectual caliber would be able to design one.
Later on, when Bane attacks Gotham's stock exchange, Bruce returns to Gotham as Batman and chases Bane and his men on the Batpod. After Batman manages to stop one of his men and recover a piece of technology, he is pursued by the police, as he is still wanted for the crimes Two-Face (aka Harvey Dent) committed in The Dark Knight. He escapes into a dark alley where the police corner him, but he escapes by flying out of the alley in the Bat. He runs into Catwoman (aka Selina Kyle) and helps her escape Bane's men.
After Bruce escapes The Pit and returns to Gotham he convinces Selina to help him get Lucius out of captivity so that he may get him access to his Batman equipment, including the Bat, which Bruce secretly parked on top of Wayne Enterprises.
When the cops return to the city from being held underground, they confront the escaped Blackgate prisoners along with Bane's mercenaries who are armed and have access to Tumblers. As one of the Tumblers takes aim at the cops, Batman arrives in the Bat and disarms it by blasting off its canon. After Selina rescues Batman from Bane, he takes off in the Bat and follows Miranda Tate, (who was really Talia al Ghul), in order to recover the fusion reactor core, which was converted into a nuclear bomb.
After Batman forces the truck holding the core to crash underground, Talia reveals she has found a way to keep the bomb on track to exploding. Batman then attaches the bomb to the Bat via a cable and flies out to the ocean to protect Gotham from the blast. After the city honors Batman as a hero and Bruce is privately mourned, Lucius discovers that Bruce had designed an auto-pilot on the original Bat when he logged in six months ago (when Lucius first told him about the vehicle), hinting that Bruce survived the blast.