Mysterious, free-to-play arcade cabinets for a video game called "Joker's Revenge" are being discovered all around Gotham City. People who play the game report that it's very fun, but are unable to remember any details about the game, or even what genre of video game it is. They do, however, all agree that Harley Quinn is an ungrateful bitch, and that she must be brought back to The Joker so that she can be correctly punished.