A closed room mystery begins when an infamous tycoon is found dead in his bath tub. The famous police lieutenant Palmu is summoned to investigate.

A rich widow is found dead in her apartment in Helsinki due to gas poisoning. The incident is initially thought to be an accident, but inspector Palmu notices that the murderer made a mistake, and so Palmu, Kokki and Virta begin the investigation: who had come to the apartment through the balcony door and opened the gas tap while Mrs. Skrof was asleep?

A man's body is found on Tähtitorninmäki in Helsinki. Palmu starts to investigate the case, but the scandalous newspaper story causes problems for the police.

A TV reporter is murdered when he is eavesdropping on a secret Finnish-Soviet conference. The National Broadcasting Corporation enlists the help of police lieutenant Palmu, who comes out of retirement for this case. However, some have their doubts about the loyalities of Palmu, seeing that he was spotted in a diplomatic soiree in Moscow just a few weeks before the murder.

Inspector Palmu gets to solve a new case, when a wealthy real estate millionaire connected to Germany is murdered in Kaivopuisto, middle of post-war Helsinki. The murder is only beginning for the events that will shake the city even more violently than Soviet bombers during the war.