Fantastic. Absolutely fantastic.

This book was a very pleasant surprise! Summarizing for Anglophones, as Francophones already know this author, this work preceded Sherlock Holmes, and is very good. While Holmes has adventure and intrigue, this book has inter-generational cooperation, and history (books)! Yes, history is important in solving criminal cases, kids! It also has language learning (ok, it has two trilingual and one at least bilingual characters, all of the languages, of course, figuring importantly in solving the case)! Apart from the mystery, obviously, there is also a case or two of impossible love, sacrifice, courage, and all of this against the backdrop of the Restoration, Napoleon, and memories of The Terrors during the French Revolution. I cannot imagine for the life of me why this work has not gained the level of appreciation that Dumas' Count of Monte Cristo has gained, as it is quite nearly as good. There is a lot of Latin cited, and this makes it worth reading again in print, which I will do via Project Gutenberg or one of the other Public Domain book sources (sorry, I have no idea whether this book is available other than in the original French, but I imagine that it must be available in at least English).

This book is very much worth learning French to read or listen to, imho.