Deep in the forest, the body of a young woman is found hanging from a tree. Major Laurene Weiss attempts to solve the mystery while also welcoming an eccentric new prosecutor to Villefranche. Together they investigate, in a town already under pressure from the recently announced closure of the local sawmill and the disappearance of the Mayor's daughter.

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. Laurθne 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 phone is found with videos showing a group of young people terrified by a macabre discovery in the forest. After the body of one of the young people is found, Laurθne and her team investigate, endeavouring to understand what went wrong on their nocturnal spree. At the same time, she tries to assess her complicated relationship with Bertrand, the town's Mayor.

Everyone is shocked by the attack on Sabine's bar by a band of robbers who came out of nowhere. While the town barricades itself in, Laurene has to find and understand what they were looking for in Villefranche. Meanwhile, Cora and the Arduinna Children follow the mysterious trucks rumbling at night through the forest.

A woman suicides on the same day that her husband is awarded a medal of honour. Laurθne suspects that this man isn't quite the hero that everyone thinks they know. She tries to discover what dark secrets he's hiding, but he's protected by the Mayor, an old childhood friend.

The father of a child with a mental disability is found dead at his farm. We're concerned for the boy's future at the same time as we seek his father's killer, but Laurene is troubled because the prosecutor Siriani has arrested Bertrand.

The investigation into the disappearance of the Mayor's daughter advances with the discovery of her body in the middle of a bizarrely staged location. While Bertrand loses control and seeks vengeance, Laurene finally gets close to the invisible enemy that she's been tracking for many years.