In der Nacht des 12.

A small town at the foot of the French Alps, it is the night of 12 October: a girl is alone on her way home from a party. As she walks through the quiet streets, a man crosses her. He pours petrol over her and has her burned alive.
Every detective at some point comes across a crime that gives him no peace, that he has to solve. For Yohan, it is this murder of Clara. With his colleague Marceau, he investigates young and older men who had an affair with Clara. All of them could have done it. They were relationships full of resentment, possessiveness or indifference. A panorama of abysses opens up for the two detectives. For Yohan, the investigation becomes an obsession. Clara's death has touched something in him that makes him doubt the world we live in. Years pass, more and more suspects come into focus, but no arrests are made. Yohan must find a way to live with the mystery and yet not give up in his search for the culprit.