Sherlock Holmes And The Voice Of Terror stars Basil Rathbone as Holmes and Nigel Bruce as Doctor Watson.
Released in 1942 and set at that time, there’s a German broadcast called The Voice Of Terror, that leads Holmes to an inside leak from the inner British war council.
It ends with the traitor being exposed as a German, who took on the identity of a British official many years previously, so that he could infiltrate the system.