What strikes fear into the hearts of those who terrorize Gotham? It used to be Batman, but something far more frightening stalks the shadows-and it's after Gotham's villains, leaving a trail of carnage through the underworld. Now, with Riddler, Penguin, Two-Face, and many more left bloodied and broken in its wake, Batman opens the case on this mysterious reptilian menace and finds himself vexed by one very important question: What on Earth is it?