After the King of Ruthenia has been assassinated, Holmes and Watson are engaged to escort his son to Europe via Algiers, aboard a transatlantic ocean liner which also carries a number of suspicious persons, any of whom may be involved in a plot to also assassinate him.
- Genre: Mystery, Crime, Thriller
- Studio: Universal Pictures
- Keyword: assassin, heir to the throne, ocean liner, black and white, knife throwing, algiers, algeria, sea voyage, assassination attempt, stolen jewelry, sherlock holmes
- Cast: Basil Rathbone, Nigel Bruce, Marjorie Riordan, Rosalind Ivan, Morton Lowry, Leslie Vincent