A free extract from the official core book of the RPG:
The Domestic is an introductory scenario designed for one player, based on Ben Aaronovitch’s short story of the same name. Choose to play as a magic-wielding police officer, nurse, or social worker in a game set in the world of Ben Aaronovitch’s hugely successful Rivers of London series.
Armed with this book, a pencil, and some roleplaying dice, you are ready to take on your first case for the Folly. No GM needed!
That's exactly what came to mind.