Holt of the Secret Service (1941) was the 16th serial released by Columbia Pictures.

Plot

A murderous gang of counterfeiters has kidnapped John Severn (played by Ray Parsons), the U.S. government's best engraver. He is forced to engrave a set of counterfeit plates, to print phony money that is virtually undetectable from genuine currency. The United States Secret Service sends its toughest agent, Jack Holt (played by himself), and his female partner, Kay Drew (Evelyn Brent), after the gang. Holt poses as escaped tough guy, Nick Farrel. Masquerading as the bickering, tough-talking Mr. and Mrs. Farrel, Holt and Drew manage to infiltrate the ruthless gang of thugs. Holt locates Severn and instructs him to keep working but as slowly as possible, to give Holt time to find the head of the crime ring. Holt takes the set of counterfeit plates in hand, and much of the action has Holt keeping the plates away from the crooks. The scenes shift from the gang's hideout in a lost canyon to a gambling ship on the high seas, to a small island country where the gang hopes to escape U.S. extradition.