Great set up and great story. This one harkens back to Holmes's desire to take a case more for the mystery than the actual payment. It is funny though that he offers Jessie Hoper a cup of tea, but from the time she gets it at 2:59 til 4:07 when he takes it away, she doesn't actually get to drink it. She even gives Holmes a 'but I'm thirsty look' at 4:08 after he puts the cup on the dresser.
Anyway, still a great episode. I also have to admit, that the villains in this series, particularly this episode and the last one, were quite evil. Great writing.