The day before chemist Dr. Hans Wynhold leaves for a six months business trip to Africa, he meets chemistry student Christa Weiden. They spend the evening together in St. Pauli and fall in love. She doesn't tell him that she'll start the next day at the chemistry laboratory he works at too, because he says he doesn't like women in "men's jobs". Only after his departure the next day Christa learns about Hans' reputation as a Don Juan. In fear that she'll lose him to another woman, she follows him... and starts a series of complications.
The young fashion illustrator Jeanette meets the chief engineer Rudolf Siebert at an artists' festival in Schwabing, but thinks he is the talented but poor painter Braubach, whom she admires and would like to support. The spoiled Siebert is happy to put up with this. This is a completely new life for him. He wants to continue playing this role, and so Braubach has to play the chief engineer in his place. But then the unsuspecting Jeanette learns the truth. She feels betrayed and is deeply hurt. Now Rudolf Siebert has to convince them that he started the game with the best of intentions and that he wants to bring it to a happy end with their help. Will she believe him?
