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?
| Actor | Role |
|---|---|
 Joel RinnePalmu | Palmu |
| MMatti RaninToivo Virta | Toivo Virta |
 Leo JokelaVäinö Kokki | Väinö Kokki |
 Elina SaloKirsti Skrof | Kirsti Skrof |
 Pentti SiimesKurt Kuurna | Kurt Kuurna |
 Saulo HaarlaKaarlo Lankela | Kaarlo Lankela |
 Risto MäkeläMustapää | Mustapää |
 Henny ValjusAlma Skrof | Alma Skrof |
| AAino MantsasIiri Salmia | Iiri Salmia |
 Toivo MäkeläLanne | Lanne |
 Pehr-Olof SirénDoctor | Doctor |
| PPia HattaraHallamaa | Hallamaa |
 Rauha RentolaAnna | Anna |
 Kullervo KalskeAra | Ara |
| EEsko MannermaaHakanen | Hakanen |
| KKirsti OrtolaJanitor's Wife | Janitor's Wife |
 Oiva LuhtalaJanitor | Janitor |
 Esko SalminenLeppä | Leppä |
| LLiisa RoineVesa | Vesa |
 Rose-Marie PrechtPihlaja | Pihlaja |
| UUti SaurioPentti Lanne | Pentti Lanne |
 Laila RihteCleaner | Cleaner |
 Jarno HiilloskorpiPostman | Postman |
| TTauno SöderHomicide Detective | Homicide Detective |
| LLeo PenttiHomicide Detective | Homicide Detective |
| RRauni MiettinenWaitress | Waitress |
| SSeveri SeppänenButler | Butler |
 Oiva SalaDrunk | Drunk |
| KKauko KokkonenPolice Officer | Police Officer |
 Yrjö TähteläYoung Man in Metropol | Young Man in Metropol |