The Adventure of the Greek Interpreter Sherlock Holmes, far from being a one-off in terms of his powers of observation and deductive reasoning, in fact has an elder brother whose skills, or so Holmes claims, outstrip even his own. As a consequence of this, Watson becomes acquainted with the Diogenes Club and his friend's brother, Mycroft. Mycroft, as Watson learns, does not have the energy of his younger brother and as a consequence is incapable of using his great skills for detective work: In spite of his inertia, the elder Holmes has often delivered the correct answer to a problem that Sherlock has brought to him.
Sherlock Holmes pastiches Friends Investigate. Mycroft Holmes, Dr John Watson and Professor George Challenger also appear in the same book. Boris Akunin's short story "The Prisoner of the Tower, or A Short But Beautiful Journey of Three Wise Men" in the "Jade Rosary Beads" compilation describes Holmes and Erast Fandorin's race to thwart a devious extortion plan by Arsène Lupin. Author Nancy Springer writes a series of novels of the adventures of Enola Holmes, the much younger teenage sister of Sherlock and Mycroft. Upon their mother's disappearance, Enola discovers that she in fact left of her own volition according to a carefully devised