Seventeen-year-old schoolgirl Sina Wolf has an affair with her married schoolteacher. When one of her friends attempts to blackmail her, she lures him to the forest and kills him. Kommissar Finke does not believe her story she fabricates and continues to investigate.

After her husband's death, Claudia Bernhold discovers that he was a blackmailer. Suddenly she has an explanation for how, despite modest income, she could afford a small villa and a relatively lavish lifestyle. During his research, Haferkamp comes across the wealthy Eckart Waarst. Could he be the blackmailed man? But how can he be blackmailed? In the files of unsolved cases, Haferkamp finds a lead, but no proof. He has to resort to a ruse.