Penguin is all about the money in Burgess Meredith's swan song. The Bat-rewatch gets caught in "Penguin's Clean Sweep."
Using the portable bat-lab (kept in a blue case handily labelled, “PORTABLE BAT-LAB”), Batman discovers that the latest batch of moolah has the bacterium for Lygerian sleeping sickness mixed into the ink. According to the guard, a shipment of money was sent to the Gotham National Bank after Penguin’s break-in. Batgirl heads to the bank while Batman and Robin go to the hospital to obtain the vaccine for Lygerian sleeping sickness. (How a batch of money managed to actually be printed and put into circulation when the entire staff has been unconscious since Penguin broke in is also left as an exercise for the viewer.)