I don't know how I missed this one over the years, but watching it today on TCM, I don't remember ever seeing it before.
THE SCARLET CLAW was written especially for the screen and not from any novel penned by Sir Arthur Conan Doyle. Turns out it's one of the very best entries in the series, up there with THE HOUND OF THE BASKERVILLES and THE ADVENTURES OF SHERLOCK HOLMES as essential Holmes films.
It has all the atmosphere one would want in a Sherlock Holmes story and a mystery that deepens as the plot goes forward but resolved in a very satisfying way by Holmes. The cast includes an excellent performance from PAUL CAVANAGH as Mr. Penrose, whose wife dies a vicious death at the hands of a killer and leads to Holmes' investigation. GERALD HAMER as a nervous postman and VICTORIA HORNE as a frightened housekeeper are also fine, as is MILES MANDER as a judge whose life is in danger from a serial killer.
Although this one takes place in Canada, it might just as well have taken place on the Dartmouth moors in Devonshire--that's the kind of atmosphere it has with plenty of mist and fog to add to the Gothic ambiance of the tale.
Well worth watching for Sherlock fans. Especially good is NIGEL BRUCE as the bumbling Dr. Watson who inadvertently helps BASIL RATHBONE from time to time. His blustery interpretation of the comic sidekick is especially well done in this caper. Rathbone, of course, is beyond reproach.