When a disturbing discovery provides a lead to a possible target, Thulin and Hess hatch a risky plan to lure the killer.

Hess uses unorthodox methods to prove a theory about the Hartung case. The detectives chase a lead linked to a text message. Rosa faces another threat.

Thulin and her reluctant new partner, Hess, investigate a gruesome murder. Politician Rosa Hartung returns to work after her daughter's disappearance.

The detectives find inconsistencies as they dig deeper into the Kristine Hartung investigation, while the threats against Rosa take a terrifying turn.

Neither Thulin nor Hess can stop thinking about the unanswered questions hanging over their case. Rosa's career unravels as a childhood memory surfaces.

As the pieces of the Chestnut Man mystery fall into place and the perpetrator's motives become clear, Thulin and Hess fight to save innocent lives.