A fanfiction written for the fandom of Sherlock Holmes, that consists of two hundred and twenty one words, the last word beginning with a "b." The name refers to the apartment shared by Sherlock and Dr. John Watson, at the address 221B Baker Street, in London. Particularly common in the fanfiction based upon the 2010&2012 BBC series, because the modernization of the setting allows interpretation of a 221B as a text message or overly long tweet.
