Captain Karl Ehrlich (John Wayne) is the master of the elderly German steam freighter ''Ergenstrasse'', docked at Sydney, Australia, on the eve of the Second World War. Ehrlich is a former career naval officer who lost his rank and position after refusing to support the current Nazism regime. As his ship prepares for sea (to avoid being interned if war is declared), he meets with an old friend, British Commander Jeff Napier (David Farrar (actor)), and Napier's German fiancée Elsa Keller (Lana Turner). Ehrlich knows Elsa has a dubious past and tries to break them up.