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?

Joel Rinne
as Palmu

Matti Ranin
as Toivo Virta

Leo Jokela
as Väinö Kokki

Elina Salo
as Kirsti Skrof

Pentti Siimes
as Kurt Kuurna

Saulo Haarla
as Kaarlo Lankela

Risto Mäkelä
as Mustapää

Henny Valjus
as Alma Skrof

Aino Mantsas
as Iiri Salmia

Toivo Mäkelä
as Lanne