The Joker, it turns out, feels the same way. So he designs an epic crime to show the world that insanity is the only sane way of reacting to the world: he shoots Commissioner Gordon's daughter, takes risque photos of her (the novel is ambiguous as to whether this is a rape scene, but it is strongly implied). They kidnap Commissioner Gordon and try to turn him insane. Of course, the Joker's plan fails when Commissioner Gordon is unbreakable and Batman catches the Joker.
My favorite part of this novel is the end (PS: spoiler alert, stop reading this review to avoid it), where Batman finally has the conversation he wants to have with the Joker. He says, "It doesn't have to end like that. I don't know what it was that bent your life out of shape, but who knows? Maybe I've been there too. Maybe I can help. We could work together. I could rehabilitate you. You needn't be out there on the edge any more. You needn't be alone. We don't have to kill each other. What do you say?" The Joker responds with a joke, that I absolutely love:
No. I'm sorry, but...No. It's too late for that. Far too late. Hahaha. Y'know, it's funny...this situation reminds me of a joke...See, there were these two guys in a lunatic asylum...and one night, one night they decided they don't like living in an asylum anymore. They decide they're going to escape! So, like, they get up onto the roof and there, just across this narrow gap, they see the rooftops of the town, stretching away in the moonlight...Now, the first guy, he jumps right across with no problem. But his friend, his friend daredn't make the leap, y'see...y'see he's afraid of falling. So then, the first guy has an idea...he says, Hey! I have my flashlight with me! I'll shine it across the gap between the buildings. You can walk along the beam and join me! B-but the second guy just shakes his head. He suh-says...he says "Wh-what do you think I am? Crazy? You'd turn it off when I was half way across!"This joke, represents, perfectly why the Joker can't stop being himself, why he has to refuse Batman's offer. Christopher Nolan went another direction with this:
He, of course, doesn't tell the joke. But, here, the Joker does note their eternal struggle; they won't kill each other and so are condemned to forever battle. I have mixed feelings about which treatment I prefer. On the one hand, in Nolan's version, I like that it's the Joker who sees this pattern and recognizes the similarities between himself and Batman. However, I like the earnestness of Moore's version, in which Batman wants this war to end, and wants it to end by helping the Joker. Ultimately, though, I think I like The Dark Knight slightly more, but would recommend The Killing Joke to anyone who enjoyed The Dark Knight. If nothing else, it provides some perspective on where The Dark Knight's Joker came from; but, seeing both Jokers offers a lot of perspective on the Joker.