Diogenes Club series "Sherlock". The Diogenes Club has appeared, in various forms, in a great many other settings, most of which take as given the Club's connection to the British Secret Service: Diogenes Club The Diogenes Club is a fictional gentleman's club created by Sir Arthur Conan Doyle and featured in several Sherlock Holmes stories, such as "The Greek Interpreter". It seems to have been named after Diogenes the Cynic (although this is never explained in the original stories) and was co-founded by Sherlock's indolent elder brother, Mycroft Holmes. The club is described by Sherlock Holmes in the story "The Adventure of
Minor Sherlock Holmes characters their relationship. She also posed as John Watson's therapist and then later revealed herself to be Eurus Holmes, and at the end of the episode shoots John Watson with a handgun. In the last episode, "The Final Problem", it is revealed that Sherrinford is in fact a high-security complex on an island to house some of the most dangerous criminals in the world, including Eurus. With Eurus having simply shot John with a tranquiliser dart, Sherlock and John stage a scenario where Mycroft will admit Eurus's existence. Mycroft explains that Eurus was the youngest child, 8 years younger than Mycroft