Choice of Basil Rathbone as Sherlock was a wise one. Nigel Bruce as Doctor Watson is equally expert. With the two key characters thus capably handled, the film has the additional asset of being well conceived and grippingly presented.Plenty of ingenuity is concentrated into two concurrent mysteries with the impossible clues not made too absurd or too obvious for mystery devotees. The ‘elementary, my dear Watson’ type of dialog is soft-pedalled for more modern phrases or understandable patter. George Zucco offers a splendid characterization as the arch-criminal and Ida Lupino is highly competent as the sole romantic figure in the mystery fable.