With the exception of Lake Laach, the volcanoes in the Eiffel should actually be extinct. So where does the gas cloud of carbon dioxide that forms in the underground tunnels of the Ofenkaulen come from? Is it related to the earthquake two days ago or is there another reason? While Gerd Bach and his friends search for the cause, Emma has to confront her past in order to protect her Berlin colleagues from assassination attempts that are actually aimed at her. Can Gerd and his team protect the local population from the extreme threat of a planned sabotage and track down the person responsible? Will Emma manage to stop the insane serial killer before he kills again?