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. In this investigation, the duo must solve a priest's murder. They find a link between the macabre murder and a martyr from the 3rd century. Camille finds a cryptic note from the killer in her jacket. A second murder occurs while relics are stolen from a nearby town.