Secret Agent X was a mysterious agent who went undercover to fight crime and the enemies of the United States. As a master of disguise, he changed his face and his identity almost constantly. Nobody actually knew who he was or what he looked like, except his Washington handler, K-9. His mission, though not necessarily his identity, is also known to spunky newspaper reporter Betty Dale. However, the police in New York city, where he frequently operates, do not know who he is and consider him an outlaw.