The plot is an original story not based on any of Sir Arthur Conan Doyle's Holmes tales.

Avoiding an assassination attempt, he hurries to Washington, D.C., with Dr. Watson to retrieve it before it falls into the hands of an "international spy ring".

Before his death, the agent managed to pass the microfilm, hidden inside a "V for Victory" matchbook, into the unwitting hands of Washington debutante and bride-to-be Nancy Partridge.

Despite moving the film to the contemporary World War II period, the roles of Sherlock Holmes and Dr. Watson were retained by Rathbone and Bruce, respectively.

[4] The film's writing duo, Lynn Riggs and Bertram Millhauser, would collaborate on a Holmes picture for the first and only time.