The Scarlet Clue - Charlie Chan

Government agent Charlie Chan is investigating a spy ring intent on stealing radar plans, which leads him to a radio station in a building also containing a radar research facility.
Stars: Sidney Toler, Mantan Moreland, Ben Carter, and Benson Fong
Mantan Moreland and Ben Carter perform a version of their nightclub routine.
A lack of a copyright notice in the film puts it in the public domain.