Super involved bad doings and blackmail in mid-19th century Paris. Fortunes are made and the terrible, terrible things people did are threatening to rise from their graves.
All the while, some kids is falling in love or being made to fall in love and at the end, it looks like nobody is going to get what they deserve—though the blackmailers may get what they've been working on for 35 years.
Engaging, a nice portrait of the times, but about one million threads to keep track of. It's worth it if you can though, because they get tied together in the prettiest bow in the sequel, 'The Champdoce Mystery'.