"The Joke's On Catwoman"
Joker and Catwoman waylay Batgirl outside the home of Karnaby Katz, and bind her in cat's whiskers. These thin wires contract when in contact with the warmth of the body, eventually choking the victim to death. They leave Batgirl on the lawn and drive off.
Gasping for air, Batgirl sees the control for the lawn sprinklers a few feet away. She rolls toward it, and nudges the switch with her chin. As the sprinklers cover her in cool water, the cat's whiskers expand, allowing her to easily remove them.
Catwoman and Joker team up to search for a legendary cache of gunpowder.