Ryszard Malewicz, a young inventor, is out of work. He had been waiting for months for a response from the ministry to which he had sent plans for his invention, an explosive of extraordinary power. Desperate Ryszard is comforted by his mother and his fiancée Maria.

Mieczysław Cybulski
Ryszard Malevich, Maria's fiancé

Maria Bogda
Maria

Lena Żelichowska
Irma, a member of the gang
Tekla Trapszo
Ryszard's Mother

Kazimierz Junosza-Stepowski
The Baron, head of the gang
Artur Socha
"Engineer", member of the gang

Stanisław Sielański
Kwiatek, the Baron's mute servant, member of the gang
Feliks Szczepański
Stefan, Ryszard's Friend
Nina Swierczewska
Julia, the Malevichs' maid

Jan Kurnakowicz
Józiuk

Helena Buczyńska
Petronela, the Malevichs' housekeeper

Wanda Jarszewska
Passenger on the train
Aldona Jasińska
Vendor

Wanda Bartówna
Malevich's neighbor (uncredited)
Jadwiga Bukojemska
(uncredited)