A German wartime biography of Rudolf Diesel, inventor of the Diesel engine. The movie links the importance of the engine to the war by starting the movie with newsreel clips of German Navy U-boats in action.

Willy Birgel
as Rudolf Diesel

Hilde Weissner
as Martha Diesel, seine Frau

Paul Wegener
as Direktor Buz

Josef Sieber
as Martin

Arthur Schröder
as Lucien Vogel

Erich Ponto
as Theodor Diesel

Hilde von Stolz
as Frau von Lorrenz

Hubert von Meyerinck
as Herr von Lorrenz

Werner Pledath
as Prof. Linde

Herbert Gernot
as Krumper