This is absolutely huge in the development of the mystery novel. The plot and the characters are well developed. You'll here the detective state fundamentals of detection that have been picked up and used ever since.
The writing is old fashioned, but it's terrific. The narration is adequate. I strongly recommend this to anyone who loves mysteries, especially classic mysteries. I really wish the rest of Anna Katherine Green's work was available on Audible.
I read all Rex Stouts books in the 70s, but fortunately I've forgotten most of them. I love them all, but this plot is particularly good.
I enjoy Shelock Holmes, and appreciate the role AC Doyle had in developing the genre. Not all the mysteries are well developed though. This one is. It's a masterpiece. The narration is outstanding. One of the best audiobooks I've had.