I will not elaborate on the plot, partly because it is better to take leave without knowing where we are going. Just know that "Alex" is divided into three very different parts, in that the reader's perspective is completely changed from one to the other. The first two are fairly standard in the genre psychopath / serial killer but the third gives us a final beautiful. A word of caution with regard to sensitive souls: it is better to read some passages diagonally to ensure a good night :-)
Small special mention for the characters, including the tying Camille Verhoeven, worth us some touches of black humor absolutely delicious.
All good French crime novel that I hope you enjoy it as much as me ...