It's the Sherlock Holmes novel transferred to the screen, directed by Maurice Elvey and starring Eile Norwood. The pair had been doing Holmes movies since 1921: 44 shorts and four features, including this, the last. I've seen a few of the shorts, and frankly they don't appeal to me. In the short stories, Holmes is a cerebral character, and the movies based on them have too many titles to be good movies.
The movies based on the novels are another matter entirely. There are plenty of melodramatic incidents, whether it be malevolent, demonic hounds or, as here, deadly dwarfs, escapes from prisons, and a high-speed chase on the River Thames. These make good grist for Elvey's cinematic mill, and he takes good advantage of his opportunities.
This may not please the purist, but there are plenty of exciting incidents not in the original novel. Nonetheless, as the movie advances and Holmes becomes less a deductive machine and more a man of action, it becomes a more interesting and exciting movie. Norwood will never be my idea of Holmes -- like first loves, we never forget our first Holmes, and Basil Rathbone was a darned good one -- but it's a pretty good movie.