Fearing that Riddler will make good on his threat to destroy the city, The Batman and Detective Yin's secret alliance is put at risk when they must work together to solve a string of riddles that have been scattered throughout Gotham.
Joker dons the costume of his greatest rival, The Batman, and terrorizes all of Gotham. When the real Batman tries to stop him, Joker injects the Dark Knight with a poison that will cause him to laugh to death unless he can create an antidote.
Penguin discovers a sonic device that allows him to turn Man-Bat into his personal slave. Meanwhile, Alfred must deal with a raccoon that has found its way into the Bat-Cave and is wreaking havoc on the electrical equipment.
Joker pirates the airwaves of Gotham in order to broadcast his crimes on TV as entertainment. When Detective Yin's overzealous new partner tries to bring down the clown prince of crime, he merely becomes Joker's latest "costar."
The Batman finds himself caught in the middle of a game of one upmanship between master thieves Ragdoll, a triple-jointed contortionist, and Catwoman. Meanwhile, Selina Kyle, Catwoman's alter ego, eyes Bruce Wayne as a possible target for future robberies.
Legend says that swamp giant Solomon Grundy will return to Gotham City on a Halloween with a lunar eclipse. Supposedly, Grundy will return to get revenge on the descendants of Gotham's founding fathers. On Halloween night, the eclipse begins, and Batman receives word that Grundy is wreaking havoc in Gotham. The caped crusader is skeptical about the legend. Still, he must battle this dangerous villain who is bent on terrorizing certain residents of the city.
Joker, Penguin and Riddler battle over control of the City. They finally decide to settle their differences by giving all of Gotham over to whoever is able to capture and discover the true identity of the Batman.