The Böttger family runs a farm in the Black Forest, with great commitment, close to nature and connected to rural traditions. When the eldest daughter Sonnhild suddenly dies, Franziska Tobler and Friedemann Berg investigate the death. Friedemann has known Volkmar Böttger since school and is impressed by how enthusiastic and principled the childhood friend manages his large family and the farm. Friedemann Berg is relieved that the family can mourn in peace because the coroner does not confirm the suspicion of incorrect diabetes treatment against the Böttgers' doctor. Franziska Tobler, however, considers the doctor's statements to be protective claims and also has other clues to keep the investigation going. The behavior of Torsten Schmidt, for example,
He and his younger sister Mechthild are conspicuously evasive when asked about Sonnhild's life and illness. In general, Franziska finds the life of the Böttgers, which is completely focused on the farm and the community, strange. Friedemann, on the other hand, comes from a Black Forest farm and can understand the commitment to smallholder agriculture and the fervor with which Volkmar Böttger talks about it. Especially since Volkmar welcomes him with open arms and wants to revive the old friendship.
When Franziska finds out that Torsten Schmidt belongs to a Heimatschutz squadron, Friedemann takes a closer look and the inspectors not only discover inconsistencies in the statements about Sonnhild's last months and her death, but also attitudes of the Böttgers, which are strongly reminiscent of the attitudes of ethnic settlers. Volkmar's commitment to Torsten now appears in a completely different light.