Familiar Plot Tropes in the Canon

James Ryder begs for mercy - and Sherlock Holmes grants it  

In plotting my own Sherlock Holmes novel recently, it struck me how many plot tropes are used repeatedly in the 60 Canonical tales. I don’t mean the 11 points in Monsignor Knox’s classic outline of the archetypical Holmes story. I mean actual plot engines, such as:

• A crime with roots in the past. I count 19 stories like this, most often a past in America (six stories), India, or Australia. The first such was A Study in Scarlet.
• Revenge, usually the motive for the above.
• A thwarted marriage. At least 10 engagements in the Canon come to nothing because of scandal, estrangement, or death. Again, it all started with Jefferson Hope.
• Holmes giving Watson an impossible assignment, then showing up on the scene to cruelly criticize him for failing to carry it out as Holmes would have. “The Disappearance of Lady Frances Carfax” is a great example.
• Unlawful entry. Commentators have argued over whether Holmes actually commits burglary, housebreaking, break and entering, or no crime at all. Whatever it is, he does it five times – from the first short story (“A Scandal in Bohemia”) to the second-last one published (“The Adventure of the Retired Colourman”).  
• Disguise. Sometimes I think Holmes just likes getting dressed up.
• Letting the criminal go free. Private eyes often take the law into their own hands, but Sherlock Holmes only does so in the name of mercy. Presumably such characters as Jack Horner and Captain Crocker are grateful.  
• The use of a MacGuffin. 

Do we feel cheated when a Canonical story uses one of these familiar devices? Not at all. We feel at home. That’s why I’m using some of them in my novel-length Holmes adventure. As to which ones, you will have to wait and see.