Well once again DC has come through on their promise. Its a compleling first issue that leaves you wanting more with great art work.
Pretty much the Joker is on a killing spree and is leaving clues for Batman as always and the Riddler is in jail being used to crack codes for the police. He sees a pattern in the Jokers murders and decides that he needs to stop the Joker before he can kill Batman and breaks out of prison to confront the Joker.
When he finds Joker he explains that niether of them can kill the Bat alone because it would leave the other feeling empty. The Riddler doesn't want the the Joker to kill Bats because then the Riddler would feel that he failed and same for the Joker.
So Riddler proposes that they work together so that they both get equal satisfaction.
The Jokes response to this was a bullet to the gut of Riddler and walks away. Somehow the Riddler survives and in the coming months an all out war between the two break out and Gotham falls into despair in the wake of these two crazies trying to kill each other for the right to kill Batman and Batman needs to stop it.
We learn at the end of the issue that the "war" itself is already over and Batman is recounting the entire story to Cat woman as he lay next to her in bed. Some bedtime story huh! I assume the coming issues will showcase what each side has done to each other and who they recruit to be on their respected sides. Obviously Batman has won but what are the fates of the two masterminds? We will have to wait and see.