On an abandoned construction site, a woman's hand protrudes from a concrete slab... At Alex's request, a block is cut out of the slab and delivered to the IML. Alex, Diane and Théo set to work to gently free the victim. She is Isabella Florès, violinist at the Bordeaux Opera and daughter of Émilien Florès, authoritarian director of the same opera. Who could have killed this woman and why did they make her disappear in the concrete? The mystery thickens when Alex discovers the body of a man buried next to Isabella's... Guided by her instinct, our forensic scientist will have to redouble her imagination to understand how, and especially why these people who seem to be opposed to each other ended up like this, linked for eternity...

In Pessac, the zoo's keeper makes a frightening discovery. He found, in the enclosure of wild animals, what would correspond to human remains. Alex is dispatched to the scene and quickly confirms that a body has been scattered throughout the zoo...