What is the Black Casebook?

Batman #664
Written by Grant Morrison
Art by Andy Kubert and Jesse Delperdang

Grant's Batman run so far has left me underwhelmed. I really am not finding it up to standards for well...Grant Morrison. I don't know if it is because he is overworked or what. I felt the same about this issue. Keep in mind, I am not saying it is bad, just not up to par of the usual Grant Morrison. This focuses on a prostitute killer cop, or at least who they think is a cop. This cop is huge and looks kinda like Bane. He knocks the shit out of Batman at the end of this issue. Batman mentions something about a black casebook, whatever this is. I think Morrison is setting up some kind of mystery and the audience is not in on what exactly Batman knows. Unless I missed something. I don't know, it got kind of confusing. The art was good and everything. Just left me underwhelmed. That's all.