The Joker, just released from prison, teams up with Catwoman. They follow the clues of an ancient riddle to retrieve a nightshirt and an antique crib, which together form a map to a hidden cache of gunpowder which they plan to use for their next crime. Batman and Robin, together with Batgirl, follow their trail, little knowing that they are about to walk right into an ambush.

Following a tip from Batgirl, the Dynamic Trio meet up at the Grimalkin Novelty Company, hideout of the Joker and Catwoman. There, they overhear the arch-criminals' plot and secretly trail them to a stash of hidden gunpowder. A careless mistake spoils the villains' evil plan, however, and they are captured and brought before the Gotham City judge. But when the jury seems less than interested in justice, courtroom mayhem ensues.