It's Halloween in Gotham. To celebrate, the city's spookiest villains (Scarecrow, Clayface, Solomon Grundy and Silver Banshee) have all joined forces and gone on a crime spree. Batman swings into action to stop them, joined by Green Arrow, Cyborg, Nightwing and Red Robin. But it seems that the fiends are working for the clown prince of crime himself: The Joker, who has a surprise of his own - A computer virus that makes all technology laugh and obey his every command! Can the heroes stop the virus before it turns all of Gotham into Jokertown?