In the small bordertown of Villefranche, lost in the heart of a large forest, crime rate is six times higher than elsewhere in the area. Each new crime Major Laurène Weiss solves with the help of her unusual team makes her sink deeper and deeper into secrets of the area.

A horrific discovery in a small town nestled high in the French Pyrenees begins to unravel a dark mystery that has been hidden for years. On an unforgiving winter morning, a group of workers discover the headless body of a horse, hanging suspended from the edge of a frozen cliff. Commandant Martin Servaz starts investigating and soon discovers a dark story of madness and revenge.

Paris, France, 1899. The corpse of an unknown woman is found in the river Seine. The investigation will push a young ambitious inspector to discover a heavy state secret.