A series of mysterious murders shakes the city. On Dirty Thursday, the kickoff of the Solothurn Carnival, the body of a young woman is found at the foot of the Krummturm. A tattoo with the number 666 leads Captain Dominik Dornach to an earlier series of murders in the red-light district, where the victims bore the same tattoo. While Dornach and his investigators follow initial leads, his daughter, who works for the UN in Iraq, becomes the target of terrorists, and Dornach's world threatens to spiral down into an ever-accelerating vortex of fear.