This Is Where I Say Goodbye — James Craig

His father is dying.
He's stuck in the middle of a gang war.
And he has to solve a case with no clues.
Welcome to the world of Inspector John Carlyle.

Work goes on the backburner for Inspector Carlyle as he tries to manage his father's final days. But when the drug dealer providing the old man's pain relief ends up dead, London's least conventional copper finds himself in the middle of a vicious East London turf war. Meantime, he is supposed to be dealing with the case of a young woman found badly beaten in an alleyway. With no idea who she is, and no clues as to her attacker, he has to get help from some unlikely sources.