A series of arsons shakes downtown Mainz. Two radio messages come in one after the other that night: Garbage cans are burning in residential areas. The flames threaten to spread to the houses. The police have to be on site quickly. The two police commissioners Sarah Schräder and Jonas Horder try to get the fire under control before the fire department arrives. Meanwhile, another garbage can is burning in the neighborhood. The Mainz Fire Devil has been causing mischief for months. When the fire was extinguished, the team from the Mainz 1 Police Department began looking for the perpetrator. Several identity checks are scheduled that night. Meanwhile, the Neustadtwache Mainz team receives a tragic radio message: a man is lying lifeless in a pool of blood. Next to him is a gun. Here, too, the police officers have to be on site quickly and clarify: Is this a crime, a murder or is this a suicide that the patrol officers find?