An unidentified body is found in the remains left after a fire in a trailer at a run-down caravan park. The owner of the trailer, a young drug-addicted woman, is missing, but is she really the victim? And what role has the so-called neighborhoods watch from the nearby community played? The case is difficult to solve, with everyone involved guarding their secrets, regardless of social class. Furthermore, police supervisor Klas Fredén decides to go over Martin Beck's head and recruit charismatic, Norwegian homicide investigator, Steinar Hovland. 

Two traffic officers on a quiet morning shift try to stop a car for speeding. When the car finally pulls over, the driver gets out and shoots at them, killing one of the officers in cold blood. A national alert is issued and an extensive search for the ruthless killer begins, with the Beck group at the lead. Neither the officer's shocked and wounded colleague nor any of the witnesses have seen anything helpful to the police. Finally, they find the car registration number using a surveillance camera. But, when they enter the car owner's apartment, they find him shot to death. The first day of summer is a long one for the Beck group, as the killer has more victims on his list.