Sherlock: The Blind Banker

It took me a bit, but after some googling I found that this episode was based on a story called "The Dancing Men." In the short story, Sherlock helps a distraught husband figure out that the dancing men he finds are a code. The code turns out to be a threat to his wife, who used to be involved with a Chicago gangster before marrying him. Sherlock is unfortunately too late, as the husband is killed in a shoot-off with the gangster. He is able to capture the gangster, though, and the wife recovers from her self-inflicted wound.

In the "Sherlock" adaptation, there is very little that is similar. The main idea, a code to be cracked, is there. But the figures do not represent letters, but numbers. They are Chinese numbers, and they refer to words in a book. There is a sympathetic female character, who is haunted by her past, so that is slightly similar. The victims of the multiple-murder episode are all part of a smuggling ring, so that is similar to the Chicago mob. The main smuggler, who turns out to be a woman, is murdered at the end of the episode by an unknown assailant who is Skype-ing with her at the time. Perhaps this storyline will return.