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.
Basil Rathbone
as Sherlock Holmes
Nigel Bruce
as Doctor Watson
Marjorie Riordan
as Sheila Woodbury
Rosalind Ivan
as Agatha Dunham
Morton Lowry
as Steward
Leslie Vincent
as Nikolas Watson
Martin Kosleck
as Mirko
Rex Evans
as Gregor
John Abbott
as Jodri
Gerald Hamer
as Kingston
William 'Wee Willie' Davis
as Gubek
Frederick Worlock
as Prime Minister
