Raymond Bannister is a wealthy man living a secure life, but the day that he receives a single slipper in an envelope his world falls apart.

He seeks out a place in the bad part of town – is he looking for his own demise? He is found slashed down in a dirty alleyway. The crime and the crime scene are inexplicable to Lestrade, and he seeks the help of his new consultant detective, Mr. Sherlock Holmes.

This beginning will lead us back in time, to India, and it will lead us to the strange origin of a group of children that call themselves the Irregulars. Is the answer to this case also the answer to the big question – who is Sherlock Holmes?

Meanwhile the emotions between Missy Hudson and John Watson are stirring, as a certain Mary Morstan seeks the help of Sherlock. A mysterious and cruel new player has entered the London underworld, his signature is just the letter M.

The Irregulars is the second instalment in the upcoming trilogy Becoming Sherlock, written by Costa shortlistee Sarah J. Naughton, under the creative direction of bestselling TV, film and novel writer Anthony Horowitz.