A young woman is found dead in a lake where legend tells of spirits dragging people into its depths. While everything points to suicide, detectives Maris Bächle and her new partner, Konrad Diener from Freudenstadt’s criminal investigation team, begin to have doubts. Their suspicions grow when another young woman crashes her bicycle into the water. As they delve deeper into the investigation, the duo discovers a chilling mystery bound up with local legends and must race against time to uncover the truth before more lives are lost.

When Hans Katrein, a retired theology professor, returns to his home in the Black Forest after years spent overseas, old secrets begin to resurface. His childhood drawings of the occupation following the end of World War II brings the past vividly to life. As the community reflect on these memories, long-buried stories re-emerge, intertwining with the present in a poignant reminder of history’s enduring impact.

Tension soars after Konrad Diener's introverted son, Emil, disappears during a camping trip. After two days of fruitless searching and a severe storm, Emil reappears, seemingly unharmed. The 14-year-old is noticeably changed however and refuses to speak about his ordeal or where he's been, leaving his family with more questions than answers.

Johannes Schindelar, a deeply unpopular tannery owner, is found drowned in a vat of lye, in a murder which resembles an execution. When fire chief Diebold meets a fiery end, investigators must piece together the connections between the two murders before more lives are lost.

A murder in a forest near Freudenstadt sparks a series of killings. The evidence leads investigators to Florentin Sneelin, a fertility doctor living in a moated castle in the village of Glatt, who knew one of the victims from a long-ago stay at a children’s convalescent home. At the castle the detectives discover the ice cellars hold more than just champagne. The past returns to haunt the present as they delve deeper, turning a peaceful small town into the backdrop of a gripping thriller.

Despite the main suspect being in custody, more frostbitten bodies appear, all with a single black gemstone placed on their left eye. Freudenstadt Detectives Maris Bächle and Konrad Diener suspect multiple perpetrators with the same motive are behind the eerie crime.