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.