Adaptations
The Granada TV series adaptation (entitled merely "The Red Circle") makes several key modifications to the short story: The episode introduces a new character (Enrico Formani, an Italian expatriate who is murdered by Gorgiano, possibly indirectly as a result of Watson blowing Formani's cover); Inspector Gregson is replaced with Inspector Hawkins; Gorgiano makes an attempt to infiltrate the Warrens' house and kidnap Emilia and is chased away by Leverton; Emilia notices Holmes and Watson in the boxroom and realizes she's been seen; Holmes enters Emilia's room and speaks with her, hearing the story of how she and her husband ended up involved with the Red Circle; Emilia arrives at the scene of the fight between Gorgiano and Gennaro before Holmes and his party do. The 1945 film Pursuit to Algiers takes some characters from this story.
Read more about this topic: The Adventure Of The Red Circle