Metropolis faces a new menace in the form of "the Unknown" -- a fiend who terrorizes the city, demanding the authorities allow bank robberies to occur, or bombings will tear through the city! Can Superman get to the bottom of things and unmask "the Unknown" before it's too late?! Well, of course he can. He's Superman. Duh. But find out how he does it as Michael looks at the 15th storyline from the Superman daily newspaper strip!