The October Man (Rivers of London #7.5), by Ben Aaronovitch

Subterranean Press, May 2019

This entry in Rivers of London is, for variety, set in Germany, and involves a German river. Or two. And river goddesses.

Tobias Winter is an investigator for  Abteilung KDA, the German version of Britain's Folly. He's on leave when he gets summoned to Trier, to investigate a possible "infraction." A man has been found dead, his body completely covered by a strange fungus, which has also invaded his lungs, causing his death.

(Tobias is Germany's equivalent of Peter Grant, not Thomas Nightingale; he's the relatively new practitioner recruited because "you can't trust the British to keep an agreement over the long term." Yes, there's competition and distrust between the magical law enforcement operations of Britain and Germany.)

Tobias Winter's liaison with the Trier police is Vanessa Sommer, who is intelligent, ambitious, and very interested when she learns that Tobi can actually do magic.

Sommer is also her unit's expert on wine and the local wine industry, more by accident than intention, and the dead man was found near a winery, and was a member of a social group called The Good Wine Drinking Association--half a dozen middle-aged men whose lives were at a standstill  in various ways. The fungus is one that is sometimes used in the wine industry.

Winter and Sommer are soon visiting the winery. The owner is the granddaughter of the last man to run it as a working winery, and has spent years in California learning the ways of the California wine industry. This doesn't include her grandfather's annual gift of wine to the local river goddess, Kelly, goddess of the River Kyll.

Investigation includes talking to Kelly, to the kindergarten-age new goddess of another river, to every surviving member of the Good Wine Drinking Association--and investigating a court scandal from more than a thousand years ago, when Kelly had taken a mortal lover.

There are more deaths, and the deaths have the inconvenient effect of eliminating suspects while not helping them zero in on the real killer, who might be an illegal practitioner, or something more frightening.

I like the characters, the story is interesting, intricate and satisfying. It's also quite fun to get the German perspective on the British and the Folly, including Tobias' study of every detail the Germans have on Detective Constable Peter Grant. It seems there's a lot of possibility for both rivalry and cooperation between the two magical law enforcement organizations. I'd really like to see some of that.

Recommended.

I received this book as a gift, and am reviewing it voluntarily.