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.
Special Detective Unit Special Detective Unit The Special Detective Unit (SDU) () is the main domestic security agency of the "Garda Síochána", the national police force of the Republic of Ireland, under the aegis of the Crime & Security Branch (CSB). It is the primary counter-terrorism and counter-espionage investigative unit within the state. The Special Detective Unit superseded the Special Branch (which they are still commonly referred to as), which itself replaced the older Criminal Investigation Department (CID), which was founded in 1921. They work in conjunction with the Defence Forces Directorate of Military Intelligence (G2) – the Republic of Ireland's national intelligence