Haarlem, a characteristic city on the river Het Spaarne, is plagued by an unknown perpetrator, who brings great fear to the city and sows death and destruction. The entire city, and all its inhabitants, are in danger, but knowledge about where and how the danger lurks remains unknown for a long time. Everything begins on King's Day, in the market square in the centre of the city, where the annual fair takes place. A complete chaos in the market square marks the beginning of a weeks-long state of emergency declared by the mayor. Because there is no clarity about the perpetrator and his motives for a long time, and multiple victims are to be mourned, a group of citizens even takes the initiative to unmask the perpetrator. From the moment a well-known Haarlemmer is kidnapped, the most horrific events follow one another. Hundreds of police officers, specialists, and experts from Haarlem and Amsterdam bite their lips raw due to the initially elusive situation. Then the mayor makes an unprecedented decision, and the hunt begins in full force.