It was no use pointing out that we were actually policemen, not gentlemen, because Nightingale has a very clear idea where one ends and the other begins. One day, I’m hoping, he’ll show me where that line is. [loc. 159]
This is a slight novella, though it does contain multiple plot strands (not all of them resolved): I think it fits between Foxglove Summer and The Hanging Tree chronologically, but there's little reference to the larger arcs of the series (Lesley, the Faceless Man, Tyburn et cetera). The Furthest Station (Cheshunt, for those without a Tube map to hand) is a nicely self-contained Rivers of London novella, with some tantalising hints of Nightingale's past (but, as usual, not enough of Nightingale's present) and some foxy friends for Abigail.
When is the next full novel due?