The latest assignment for respected detective Charlie Chan has come directly from the government and involves the disappearance of a scientist named Harper, who was working on an extremely important serum. When the scientist is killed, Chan must sort through all very likely suspects, including the man's sister and his butler.

• Monogram Pictures
• Sidney Toler
• Mantan Moreland
• Edwin Luke
• Hardie Albright
• Janet Warren
• Al Bridge
• Edith Evanson
• Dorothy Granger