Batman, Vol. 1

When Batman investigates a string of missing prostitutes, who were apparently entertaining a Gotham City Police officer, he finds himself face to face with a mysterious, silent giant. Unable to stop the figure, and trying to avoid his death at it's hands, he realizes that this is connected to the Gotham City Police officer who shot the joker... and that both cases are related to the files in the black casebook. But what is the black casebook?