The Dynamic Duo are tied to a conveyor belt of a hole punching machine that creates paper music rolls for player pianos. Batman observes how the machine operates, and deduces a clever way of evading perforation by calculating the notes necessary to make the plunging punches miss and then overpowering the sound of the piano. When he and Robin capture Harry, Harry squeals that a guy named Fingers is the ring leader. Batman deduces that Fingers and Chantell are the same man, and soon unravels the rest of the evil plot.