The Bureau of Secret Projects has been tasked with identifying and arresting a powerful criminal known as "Mr. Big", breaking up his syndicate. Department head Mr. Reed brings in weakling gas attendant Stanley Beamish, the only test subject who can successfully turn into Mr. Terrific. The superhero discovers Mr. Big is a woman (Kathie Browne) but exclaims aloud and is forced to flee, leaving behind a coupon for his gas station. Two of Mr. Big's men force Stanley, Hal, Mr. Reed, and Mr. Trent to her mansion. Mr. Big reveals she was widowed by the actual Mr. Big who left the syndicate to her upon his death. She says she wants to escape, but first must find who is Mr. Terrific. Hal is too preoccupied with her beauty to fall for the trap. Stanley must find a way to become Mr. Terrific and rescue the situation.
Like the opener, a silly, shaky plot, but there's some comedic moments.