When the fire brigade is called to a burning shed in the Black Forest idyll of Kirchzarten, a volunteer is killed as a weapons cache beneath it explodes. Louise Boni, back with Freiburg Kripo after treatment and recuperation for her alcoholism, is assigned to the task force dealing with this case. The meagre evidence they have points to a possible connection with German neo-Nazis or illegal arms dealers from the former Yugoslavia, while the arrival of secret service agents suggests more is at stake. For Louise to solve the riddle she needs to overcome the ghosts of her past that continue to haunt her.