My last read was Émile Gaboriau's La corde au cou (it has three different English titles, I think dependgin on the edition: Rope Around His Neck / In Peril of His Life / In Deadly Peril) and I must it was simply brilliant. Even if you have the skills to find out who the murderer is, it is anything but excitement reducing.
Despite being a bit theatrical (but you might as well forgive this since the book was originally published in 1873) the storyline is very dynamical, full of conversations and even the descriptions are easy and nice to read. Even if you know the end can't be bad, you find yourself crossing fingers and your mind is so focused on the events of the book you actually have dreams about it at night. I have read many, many novels written in the same era yet none of them resulted so fresh, so exciting, so modernly written.
There is also a TV miniseries and though I have not seen it, there is a picture from it on the cover of my book and while reading it I usually stopped and stared at it for a long time, all this because the face of the actor who played Jacques de Boiscoran (Bruno Devoldère) was so eye-catiching and mesmerizing (at least for me, and don't ask me why).
The novel might be hard to get but if you happen to run into it somewhere, let it be a new or a secondhand version, I recommend it with all my heart and soul.