The Blind Beak of Bow Street was the common name among the criminal class of London in the mid-eighteenth century for Sir John Fielding. As a magistrate, he was known and respected by them for being firm but fair. He was knighted for creating the first police force in London, the Bow Street Runners.
He was the half-brother of Henry Fielding, also a magistrate. Blinded in an accident when he was 19, he was his brother's assistant and when Henry died became a magistrate himself. All in all he was as interesting a character to choose for your detective as you could find in Georgian England.
In Murder in Grub Street Bruce Alexander (a pseudonym for Bruce Cook who, alas, died in 2002) has provided a gory massacre of a printer and his wife, his children, and his apprentices. Who would do such a thing? What motive could there be? An eccentric poet is found on the scene in a bloody nightshirt holding a bloody axe. It's obvious he did it, no?
No. Sir John, with the help of Jeremy Proctor, a 13-year old who was to have become an apprentice in the dead man's household, believes the poet is innocent and figures out who actually did the crime fairly early in the story. But there is no evidence. No first-person witnesses.
With with Jeremy's help and the backup of the Bow Street Runners, Sir John is able to get the evidence he needs to convince the chief magistrate that the poet didn't kill anybody. Meanwhile we meet some fascinating characters who are I believe authentic to the period: the owner of a gambling den, a barrow woman, the 18th century equivalent of an undertaker, a petty thief who teaches Jeremy some of the argot of the street, and a reform-minded prostitute. All help in one way or another to bring the story to a happy ending. An ending that includes a shocker in the very last paragraph.