Discovering that he is a double for the King Rudolph of Boravia who fled his castle, Hendrickson agrees to take the king's place to avoid unrest. But when the real king is captured by the Iron Duke, the Blackhawks are called to the rescue.
A man's face changes colors when in the vicinity of someone lying. He aids the police until gangland hears of his ability and kidnaps him. As he escapes from them, he hits high-voltage wires and loses his ability.