The Yellow Mask has a personal vendetta against Clark Kent, but by working with Nazi spies, he can take care of his nemesis, and help to steal a marvelous American invention. A 10 foot tall robot is capable of flying under propeller power, and fighting battles with little harm to itself. A scientist discusses the abilities, but finds himself at the gun point of the Yellow Mask.
Posing as a government official, the Yellow Mask steals the blueprints of the invention. Has he thought of everything in his theft of the mechanical man to make a clean get away?
Elsewhere, Clark and Perry get word of the theft at the hand of the Yellow Mask. Can they keep sitting idly by, and leave his capture up to the police? National security is at stake.