Basil Rathbone as Sherlock Holmes and Nigel Bruce as Dr. John Watson appear in this third feature based loosely on Conan Doyle's short story "His Last Bow," and featuring Evelyn Ankers (The Wolf Man). Set during WWII, a Nazi agent broadcasts under the mysterious name of the "voice of terror," and attempts to sabotage England's efforts. Homes uncovers a mole and a German spy, and proceeds to unmask the terrorist.