A computer virus has been attached to the Tampere tramway control. Virus messes up the entire test-phase operation of the tramway and causes a power outage.
As if Koskinen wasn't busy enough, a nightmare scenario takes place in the Hervanta area, Tampere: a 16-year-old girl is found strangled with a fishing line.
Koskinen's former colleague Roine has been admitted to a mental hospital. When the patients start to die of strange heart attacks, the old criminal investigator's suspicions are aroused.