Created by Moore and Bolland as their own take on the Joker’s source and psychology, The Killing Joke provides an origin story for the supervillain the Joker, loosely adapted from the 1951 story arc “The Man Behind the Red Hood!”. It was released on March 29, 1988. Taking place over two timelines, The Killing Joke depicts the Joker attempting to drive Jim Gordon insane and Batman’s desperate attempt to stop him. It became famous for its origin of the Joker as a tragic character; a family man and failed comedian who suffered “one bad day” that finally drove him insane. Moore stated that he attempted to show the similarities and contrasts between the two characters. The story’s effects on the mainstream Batman continuity also included the shooting and paralysis of Barbara Gordon. The book explores Moore’s assertion that, psychologically, “Batman and the Joker are mirror images of each other”. The comic book, however, delves deeper in order to present Batman’s own psychology - that he is, in his own way, just as insane as the Joker, and that he and the Joker perceive the world according to differing points of view, with the Joker’s interpreted through a joke.