Aliens from Outer Space are slowly switching places with real humans -- one of the first being a young man about to get married. Slowly, his new wife realizes something is wrong, and her suspicions are confirmed when her husband's odd behaviour begins to show up in other townspeople.

The attractive Oberleutnant Paul Wendlandt is stationed in North Africa as a fighter pilot. While in Berlin to deliver a report he is given a day's leave, and on the stage of the cabaret theatre "Skala" sees the popular Danish singer Hanna Holberg. For Paul it is love at first sight. When Hanna visits friends after the end of the performance, he follows her, and speaks to her in the U-Bahn. After the party in her friends' flat, he accompanies her home and chance throws them further together when an air raid warning forces them to take cover in the air raid shelter. Hanna reciprocates Paul's feelings, but after a night spent together Paul has to return immediately to the front. There now follows a whole series of misunderstandings, and one missed opportunity after another. While Hanna waits in vain for some sign of life from Paul, he is flying on missions in North Africa. When he tries to visit her in her Berlin flat, she is giving a Christmas concert in Paris.