S02E39 — The Penguin Declines

Batman, summoning all the strength he can muster, breaks his chains and frees Robin from the giant clam. The heroes arrange for the Joker's former confederate, Venus, to stay at an apartment while they figure out what to do next. Meanwhile, the Joker has freed the Penguin from Gotham State Prison to continue their crime wave. The Joker tricks Venus into asking Batman to take her to the Batcave. The Dynamic Duo take her to their base of operations (but only after making her fall asleep first). When they arrive, the Joker, Penguin and assorted thugs are revealed to be hiding in the Batmobile's trunk. Batman, however, anticipated this and none of the criminals know where the Batcave is. A figure erupts, with Batman and Robin finally ending the zodiac crimes.