Vladimír Ráž
— Dr. Václav Pánek
Václav Voska
— Dr. Vladimír Gajdos
Irena Kačírková
— Dr. Lída Kafková
Rudolf Deyl
— Sebek - captain of SNB
Zora Polanová
— Marie Bosáková - assistant
Jan Pivec
— Driver Hába
Ladislav Pešek
— Karel Chládek
Vladimír Hlavatý
— Janitor
Jaroslav Marvan
— Zouplna
Felix le Breux
— Director
Miloš Nedbal
— Ing. Karel Vlach
Ferdinand Krůta
— Laboratory
Mirko Musil
— Policeman
Jan Maška
— Investigator #1
Miloš Vavruška
— Investigator #2
Zdeněk Jelínek
— Guest
Karel Krautgartner
— Musician
Jiří Verberger
— Hudebník-pianista
Karel Turnovský
— Drummer
Adolf Šmíd
— Trumpetista
Josef Steigl
Antonín Zíb
— Commentary (voice)