The Nancy Drew books (in their earlier incarnations) were one of my early reading addictions -- at one point I owned most of them and devoured them eagerly. No matter that the characters were completely one dimensional and the plots predictable -- Nancy was a take-charge, redoubtable heroine who ran the show without having to rely on others. I adored the books -- even though I find them pretty much unreadable now.
What you have is the PHRYNE FISHER BOOKS by Kerry Greenwood -- twenty plus gloriously entertaining confections.
I received the first four as a Christmas present and have been galloping through them much as I used to gallop through Nancy Drew. This isn't great or challenging writing but I found the books compulsively readable. Phryne is, like Nancy, pretty much one-dimensional and the plots are predictable - at least in these first four books -- there are many more in the series which I'll be reading soon. (There's a TV series as well but I haven't seen it--yet.)
As I said, lots of fun!