1495: In the peaceful medieval city of Zons, on the banks of the Rhine, a young woman is found hanging from a parapet, raped and mutilated. A month later, another maiden falls prey. Bastian Muhlenberg, head of the City Guard, is determined to decipher the murderer's gruesome code, unaware that he and the woman he loves are in the killer's sights. With the help of an old psychic, a priest, and the stars above, Muhlenberg must solve the "fatal puzzle" before it's too late.

Present day: Journalist Emily Richter is thrilled when she's assigned a series of articles about the historic Zons killings. However, right before her stories are to be published, a young woman's body is found hanging from a city tower-grossly maimed and wearing a linen gown, like her medieval predecessors. Detective Oliver Bergmann leads the investigation, tapping the knowledge of the attractive young journalist. Working together-and using Muhlenberg's old notes-they race to stay one step ahead of the copycat killer.