The October Man, by Ben Aaronovitch

Although it references to the Rivers of London characters, this novella and short story is actually more Rivers of Germany. It features Peter Grant’s German counterpart Tobias Winter, investigating a mysterious vineyard death in the Mosel valley. His local police liaison is Vanessa Summer, a pragmatic offsider who makes a useful ally and potential recruit. While the story is a bit of fun, its chief role is in providing a deeper and richer backdrop to the Rivers of London world, filling in some gaps on postwar relationships and developments in magical communities. It would be great to see Peter Grant and Tobias Winter meet up and even work together in a future tale, so hopefully that is where the series is heading as the ranks of the international magical police expand.