Rosa Wilder returns to her hometown Oberwies to care for her father Paul during his chemotherapy, taking command of the local police station. When village officer Urs Betschart is found murdered in the forest, what appears to be a car accident reveals itself as a brutal beating. The investigation takes a sinister turn when a sawn-off, bloody wild boar head is thrown through the police station window onto Betsch's desk—a clear threat.

Reinforcements arrive from the city in the form of Kägi, but Rosa soon discovers he's meeting secretly with informant Franz Ramser, a construction worker who contacted Federal Police about region-wide corruption. For years, massive price-fixing has plagued building projects, orchestrated by Räber AG in a multi-million fraud scheme. Kägi suspects Betsch's murder connects to this construction cartel—potentially run by Tim, father of Rosa's son.

Developer Thomas Gmür becomes a prime suspect after his loud argument with Betsch on the night of the murder. Gmür, an alcoholic since his business partner's death three years ago, faces company ruin and family disintegration. Meanwhile, Dani and Robert Räber face blackmail over documents exposing their mafia-style construction cartel.

As Rosa battles the case, her father Paul's cancer worsens and he refuses further chemotherapy, preferring dignity over treatment. The investigation reaches a terrifying climax when her son Tim finds himself in mortal danger, forcing Rosa to confront enemies on all fronts.