In this movie, Batman is already a silent guardian of Gotham. However, this version is truly mysterious, only operating at night and keeping himself in the shadows. It is almost like he is in 1989's Batman, with the police knocking down questions about him and only tabloid reporters saying he exists. He is truly a shadow.
Bruce Wayne comes to Metropolis for a meeting with billionaire Lex Luthor. Being the genius he is, Luthor has figured out Superman's weakness, getting a chunk of kyrptonite from when Zod tried to turn Earth into Krypton. Luthor asks Wayne if his Research and Development team can create a suit made of the rock. He doesn't trust Superman, and wants to be able to take him down if necessary. Wayne agrees that Superman is a bit suspicious and takes the kryptonite to create the suit.
Wayne takes a piece of kyrptonite as protection against Superman. In the night Batman goes out, and talks to Superman, telling him his suspicions, saying that he can't have no back story, and that he intends to find it.
Meanwhile, Clark Kent is now working at the Planet with Lois, who already knows the truth. Clark and her go to a fundraiser dinner run by the Wayne Foundation. There, Clark and Bruce talk, while Lois flirts with Wayne. Bruce then realizes the truth about Clark, saying that his true mask isn't a good one.
The movie goes on, with both Superman and Batman rivaling each other, leading to an epic battle with Lex Luthor in his battle suit. The movie would end with Batman and Superman forming a permanent alliance, and the first photo of the Batman being leaked, thus exposing him to the world.