Batman: The Audio Adventures #2

Batman comes face-to-face with the ninjas who have been tearing through the Gotham underworld. As the Dark Knight stares down the menacing assailants, he learns more about their mission as well as the name of the one they serve: the Demon's Head, Ra's al Ghul. Meanwhile, something prowls the sewers of Gotham City, a being whose mind has been warped by The Joker's dark purple dawn!