After a missed call and a disturbing voicemail from his former colleague Hella Christensen, investigator Simon Kessler heads to Nordholm to check on her. His instinct tells him something is wrong. Her son Sven and her sister Rieke cannot reach her either. The sisters, who haven't had any contact for years, have a few things to clarify after the death of their father.

After initial problems in Nordholm's police station, Simon Kessler and Commissioner Lena Jansen pull themselves together and investigate together against Thomas Haller and his wife Maria on suspicion of large-scale welfare fraud. There seem to have been falsified accounts for years that nobody noticed - except for Hella, who had an affair with Thomas. Like Hella, the Hallers own a boat with which Thomas often traveled the Baltic Sea. Could he have met her on the open sea? Was he aware that his wife knew about his relationship with Hella?