A young woman is found hung in the forest and Laurène and her team try to solve the case while welcoming the new prosecutor. There's more to solve: the disappearance of the mayor's daughter, and Laurène’s own kidnapping 20 years ago.

Laurene comes face to face with a wolf which appears to be guarding a newborn baby hidden in a box. She undertakes to find the baby's parents, followed from afar by the mysterious animal. As everything rapidly becomes complicated, memories from her troubled past resurface.

An amateur caver emerges traumatised from a labyrinth of subterranean grottos where he says he lost his friend. Laurene tries to unravel fact from fiction in his witness statement before contemplating a perilous descent. At the same time, Cora thinks that the Mayor's daughter has been kidnapped by a mysterious group of activists who are leaving their marks on the walls of Villefranche.

A traditional ritual of a school with mortals, which is producing tension in the city. Cora has visions of an underground network.

A Sabine barless shootout causes a hunt for a band of armed criminals. Cora and Romano spy on trucks that enter the forest each night.

A wife of a hero commits suicide locally. Laurelyne is sure that he is not what he appears to be and investigates on his own.

The truth about Marion finally comes to the surface. Bertrand gets violent. Lauren and Cora are caught in a dangerous plot.