A new villain called the Cluemaster has reared his head in Gotham, robbing museums and banks while leaving clues behind at every crime scene. At first, everyone is sure that Riddler is in cahoots with this new villain, due to their very similar calling cards. However, when Riddler finds out about this, he's outraged and insulted, and even offers Batman help in stopping Cluemaster. Unfortunately for him, Batman refuses his offer. Deciding to take matters into his own hands, Riddler breaks out of Arkham and tries to stop Cluemaster's latest robbery. When the two finally meet, Riddler finds out that the Cluemaster is actually one of his former henchmen, Arthur Brown. Arthur was fired from Riddler's gang for being too ambitious and insulting him, and now he wants payback. In order to takedown Arthur, Riddler & Batman reluctantly join forces. They even get help from Brown's daughter, Stephanie, who hates her father. At the end of the movie, Stephanie decides to become a vigilante, calling herself Spoiler.
