Posing as a spy in Switzerland, Sherlock Holmes (Basil Rathbone) brings a scientist and his revolutionary bombsight to Britain, but it turns out that Professor Moriarty (Lionel Atwill) also wants the invention in order to sell it to the Nazis. The fourth film in the series reintroduces Moriarty after The Adventures of Sherlock Holmes (1939), but with a different actor. The professor is well suited as someone who would sell wartime secrets without any concern for king and country, even if Atwill isn’t particularly memorable. Still, the cat-and-mouse game between him and Holmes is the central part of a good story, and the finale is dramatic.  

1942-U.S. 68 min. B/W. Directed by Roy William Neill. Story: Arthur Conan Doyle (”The Dancing Men”). Cast: Basil Rathbone (Sherlock Holmes), Nigel Bruce (John Watson), Lionel Atwill (Professor Moriarty), Kaaren Verne, William Post, Jr., Dennis Hoey.

Trivia: Followed by Sherlock Holmes in Washington (1943).

IMDb