Rügen in the summer of 2003. The island is shaken by a series of mysterious murders of women. The peculiarities of the murders point to a similar crime that forensic scientist Albert Pirell investigated thirteen years ago. Until his death, he was haunted by the question of how the victims—clearly a couple in love—died. Pirell's granddaughter Leona, who has followed in her grandfather's footsteps, has resumed his research. Her attempt to shed light on the mysterious darkness takes the young forensic scientist to the island of Rügen, where she meets retired detective Henning Lüders. Finally, she manages to uncover the true cause of death. But will this knowledge alone lead the police to the perpetrator? Time is of the essence, as another victim has already been mourned.