A woman is found dead in the steam room of a spa. She looks 20 years younger than she is. Investigations take Niémans and Delaunay to the next village.

The body of another spa client is found. What's the connection between the village, the spa director whose clients are being killed and the legends that seem to terrify everyone?

Niémans and Delaunay explore the dark side of the human soul, along a road dotted with unexplained deaths. Their bond strengthens when Camille's son gets into a desperate situation.

Camille finds a cryptic note from the killer in her jacket. A second murder occurs while relics are stolen from a nearby town.

The body of a black woman is discovered with a hash symbol carved into her forehead. Investigations lead the detectives to a migrant camp.

Camille meets the Professor, an authority figure at the camp. When a second body is found, the mystery deepens. A demon myth is terrifying the migrant camp. His calling card is a carved hash symbol.

The butler of the Monferville estate finds a 17-year-old in a pitiful condition. The teenager claims to be Herminien, a son of the family who disappeared 6 years ago. Camille is looking for her son Léo.