I consider this among the best appearances of Rathbone and Bruce portraying “Holmes” and “Watson.” It might be due to the increased screen presence afforded to the likable Nigel Bruce; he even performs "The Bonny Banks of Loch Lomond" as they set out on a risky journey to return the King of Rovinia to his homeland after his father’s death. To ostensibly evade detection, they travel from Britain to Algiers with the intention of secretly transporting their royal passenger. Needless to say, things don't go according to plan! We are treated to some amusing adventures at sea and a captivating secondary storyline along the way. Rosalind Ivan deserves recognition for her strong performance as “Miss Dunham,” and Martin Kosleck is excellent as the unsavory "Mirko," both contributing to the enjoyment of this film, which runs just over an hour. It may not appeal to those who adhere strictly to Holmesian tradition, but it’s still a diverting piece of entertainment.

Source on TMDB