Kind of like what was said above, only a few differences:
Sal Maroni and Rupert Thorne are vying for control of Falcone's old turf. At first, it looks like it will be evenly split between the two and it will be done peacefully, but then murders happen on both sides.
A mob war breaks out in Gotham City. Meanwhile, there is also a serial killer on the loose calling himself the Joker. Batman has been searching for him for months, but the new mob war has to take prioity because many lives are being lost. Realizing that he can't search for Joker and stop a mob war by himself, he gets Gordon, and the new D.A Dent to help him. They decide that the best way to stop the gang war is by cutting them off from their weapons supplier. Batman goes to find out who is supplying each gang.
Meanwhile, Bruce is so pre-occupied with all the things he has to do as Batman that he almost completely neglects his duties at Wayne Enterprises. Instead of going in to work, he just goes back down to the cave to investigate some more. ALfred starts notcing that when he is in teh cave, he is almost a completely different person, and that persona is starting to show in teh manor as well. Alfred tries to remind Batman that Bruce is just as big a part of his life as Batman is, but Bruce waves him off. Fox is covering for Bruce at the company, but Earle comes back trying to make a hostile takeover of the company with Roman Sionis backing him.
Batman finds out that a british arms dealer named Cobblepot is backing both gangs and thinks that he might've started the gang war by killing people on both sides since he would directly profit from the war. He tracks down Penguin to his base at the docks and goes undercover working there as a new dock hand named "Matches Malone" he sets up listening devices everywhere and eventually finds out that there is going to be a big arms deal made to the Maroni gang. It'll take place in teh one area where no cops go: the Narrows, at the abandoned mental institution: Arkham.
Bats tells this to Dent and Gordon, but both say there is no way Loeb will alllow for police to go there. Dent says that it won't stop him, and Gordon agrees that he will go too, and that he will try and find some honest cops to tag along. Bats shows them a lay out of Arkham and whee they should go. He lets them know that while they won't see him, he'll be there.
At Arkham, we see Harvey, Gordon, and large detective name Bullock, and a young cop named Montoya that looks scarred out of her wits. They enter Arkhamand find the area where the transfer will be made. They wait for the gang and Penguin to show. Penguin finally shows up but instead of Maroni, Thorne shows up instead. Penguin is flustered, but is trying to wave it off when Maroni's gang comes in also. Both gangs are at gunpoint now and there is utter chaos. Penguin is asking Thorne how he knew to come here, Thorne sayign he was invited, Maroni asking Penguin if he was dealing to both gangs and why Penguin invited both gangs. At this last question Penguin looks confused and says he though coming here was Maroni's idea.
At this point we hear laughter echoing throughout the gigantic room. Gunfire erupts and maroni's, thorne's, and penguin's men start to go down. Eventually it stops and Joker walks in. He welcomes the crime lords to his humble abode. He tells them that inviting them all here was his idea. He wants to let them know that while they are fighting over gotham, the Narrows is his turf. He says that since everybody is already crazy from fear gas, that this is practically his Candy Land. And there is no better place than Arkham to be his castle.
At seeing Joker, Dent can't wait any longer and rushes in to arrest the crime lords and the Serial killer. Gordon, Bullock, and Montoya follow and a new fight ensues between the cops, the rest of the mafias men that aren't dead, and the Joker's men. Joker watches on amused at the few cops that are here to arrest them, when Batman crashes through the window to help them out. Joker is instantly angry that Batman had a better entrance than him, and tells his henchman to fall back. Maroni, Penguin, and Joer all manage to escape in different ways witgh some of their men, but Thorne is captured.
Since one of the biggest crime lords was captured, it became a huge bust on all the cops and Dent's parts. Dent was instantly catapulted to fame in Gotham, and vowed that he will bring down Maroni also, and the Joker.
It's now Christmas time and we see that neither Maroni or Joker have been caught. Batman is spending even more time trying to find out who the Joker is and his motives for killing people, but still has no luck. One day, Dent comes home and finds Joker in his living room decorating the tree with his wife Gilda tied up next to him. Dent becomes enraged and attacks the Joker, but Joker just laughs it off and grabs a lamp froma nearby table and starts to get the upper hand in the fight. Joker starts beating Dent mercilessly while singing Christmas Carols. Eventually he stops and Dent is a bloody mess. he asks him one question: Who's Batman? Dent says Joker can rot in hell. Joker just laughs hysterically at this and then walks over to Gilda and smashes the lamp in her face." Who is Batman?" he asks Dent again, and Dent pleads with Joker to stop. He tells him he doesn't know who he is, he just meets with him sometimes. Joker walks over to Dent again looking very angry. "Dammit, you weren't supposed to cave that early! I wanted to have more fun!' At this he hits dent hard and knocks him out.
Dent wakes up in the hospital and sees Gilda (with some stitches on her face) sitting next to him. Dent asks if she's ok and she nods with tears in her eyes. Dent gets extremely angry, and tries getting up, but Gilda just hugs him and doesn't let go until he has calmed down. When he is finally calm, she tells him "He stole all the presents too". dent jsut closes his eyes and hugs her.
* I have a general idea of what happens next, but I am still fleshing it out. I'll post it later*
