The Duo escape from certain death in the metal crusher and need to find where the Penguin and Marsha are hiding. A report of lizards near a park suggests Aunt Hilda and her potion-making skills. But the crimefighters only find one man there, trying to rob his boss. From him, the determine where the Penguin will strike. But the wily villain locks himself INSIDE the sub-treasury vault. Content to wait him out, Batman is unprepared for what emerges - a solid gold tank constructed from the bullion in the vault, using the secret plans from the Hexagon!