Fantômas

Particularly enjoyable because of how stereotypical the book starts out. "Of course nobody could have possibly killed the woman for these ten reasons, and she was always so careful not to be killed". But persevere through that and the story goes in many interesting and novel directions.

The book is available for free even in English presumably as public domain. However, the translation is hard to bear as the translator insisted on using stereotypical British words like chap, egad, and so on liberally throughout the book.

Next time I'd pay for a better translation.