It is a bitterly cold winter evening when Tim, Karl, Gaby, and Klösschen arrive at the scene of a tragic accident: the well-known confectioner Wolf Behrendt has apparently just fallen into an icy river and drowned. However, several days later, he has still not been found—neither dead nor alive. TKKG have doubts about the accident theory and begin their own investigations, especially since the police are busy with another matter. A mysterious grim reaper has been spreading fear and terror in the million-strong city for days and is predicting truly dreadful Christmases. As his eerie appearances increase, the baker's widow Martha Behrendt becomes more and more entangled in contradictions. When Karl suddenly disappears without a trace, it becomes clear that the young detectives are on the trail of something significant.