In a Berlin hotel a man is beaten up, but it's more than a random assault and the attacker escapes undetected. When the trail leads to Freiburg, Chief Inspector Louise Bonì is sent to investigate.

It's a complex case, a professional job. The victim is a secret service informer, the only witness knows more than she's saying, and the intelligence service is hovering in the background, refusing to cooperate. Industrial espionage appears to be at play, focused on the booming solar-energy sector.