One of 12 stories in The Memoirs of Sherlock Holmes, first published in The Strand Magazine and Harper's Weekly in September 1893. Doyle ranked it 17th among his favorite Holmes tales.

During a casual chat, Watson learns that Sherlock's older brother Mycroft has even greater powers of observation and deduction. Watson meets Mycroft and discovers the Diogenes Club, where Mycroft spends much of his time. Unlike Sherlock, Mycroft lacks the energy for detective work and prefers to observe rather than act.