When The Mystery Machine breaks down (as is expected) the gang bump into smugglers (loading crates into an airplane), Batman and Robin, a little old lady, and a punching clown filled with counterfeit cash. A tip leads them to the carnival. . .where they find Joker and Penguin behind the kooky counterfeit caper. As is usually the case with these villainous villains, our heroes wind up in a funhouse hideout.