Medieval Kollis plunged into darkness because a chain of brutal murders remained unsolved—the mysterious killer always slipped away. One night, under the light of the moon, seventeen-year-old Katrin accidentally becomes a witness to another crime. The investigation is taken up by Simon, a young man with a mystical past and outstanding analytical abilities. He needs Katrin’s help to unravel the killer’s motives. But Simon doesn’t know that on that night a rare magical gift awakened in Katrin—one she is forced to hide, since the use of moon magic is forbidden. By joining forces, they set out on a dangerous journey through the dark corners of the murderer’s mind.