The film concentrates on the destruction and the suffering of the civilians caused by modern warfare as well as on the importance of spies in enforcing a blockade under uboat surveillance.
Norma, daughter of an international spy, falls in love with Marco, a peasent fighting for his country. When Norma discovers what misery she has helped to bring about, she reveals the spies' hiding place to Marco. Meanwhile high-ranking officers are in collusion with enemy agents.