Argggh! I was not informed!!
Late last decade, Dave Duncan wrote a wonderfully atmospheric trilogy of books set in a late Renaissance alternate Venice where magic works. (A little bit.) They are also darned good mysteries.
Alfeo Zeno is a nobleman low on cash, working as an apprentice to a scholarly physician, astrologer, diviner, and magician descended from Nostradamus. The good doctor almost never leaves his house to see clients, so Alfeo has to be his Archie Goodwin. (And yes, I do mean that literally!)
Alfeo also gets frustrating assistance from his girlfriend, a courtesan named Violetta. She has as many facets to her personality as a table full of roleplaying dice, and Duncan has a lot of fun portraying this.
The three books are The Alchemist’s Apprentice, The Alchemist’s Code, and The Alchemist’s Pursuit. I just bought the last of the three at Dollar General, but they are still available in various formats on Amazon. There’s also an audiobook on Audible. All the books stand alone, and they obviously could have been an awesome fantasy mystery series that went on for years.
Dave Duncan is underrated, because his books are short and entertaining and numerous and likeable. (Horrors!) But they contain a lot of depth, the last couple decades. He has now written and published 50 books. Amazon and some independent folks are publishing him now, which explains why I haven’t seen his stuff advertised for a while.