A mutilated corpse is found during a forest hunting party and it seems the victim was the heir to a family fortune. As Niemans and Camille question his immediate circle, his sister is also targeted.

In a wine-growing region at harvest time, a battered corpse is discovered under rubble when a vault collapses during the renovation of a chapel, destroying a fresco. Was it an accident or foul play?

When Niemans obtains X-ray images of the damaged frescos, they provide further insight into the case, but does a missing fragment from the biblical scenes portrayed hold the key to the killer?

When two men discover the severed hand of a child, Niemans and Camille find the local police distracted by the case of a serial killer armed with a rifle. Can they find clues at a children's home?

Two more people are shot dead, in the cemetery: a married couple who took in foster children. But a quotation from an ancient tale about an ill-fated group of children on a memorial provides a clue.

Niemans witnesses the death of a monk named Brother Guillaume who utters the words 'the sword and the snake' with his dying breath and has the palm of his left hand burned to hide a mysterious tattoo

It seems the monks believe they have discovered sinister secret messages in the ancient music they've been studying. As Camille and Niemans get closer to the truth, they encounter a satanic sect.