A mysterious magnetic spool found during a construction project is discovered to have originated from Venus. A rocket expedition to Venus is launched to discover the origin of the spool and the race that created it.

Oldřich Lukešas Prof. Harringway Hawling
Ignacy Machowskias Prof. Saltyk
Mikhail Postnikovas Prof. Arsenew
Kurt Rackelmannas Prof. Sikarna
Günther Simonas Robert Brinkmann, deutscher Pilot
Lucyna Winnickaas Joan Moran
Yoko Tanias Sumiko Ogimura, japanische Ärztin
Ruth-Maria Kubitschekas Frau Arsenjew
Joachim Hasler