Bello is an unemployed young man living in Berlin in the early 1930s. Although his girlfriend Frieda is underage, she goes out onto the streets in order to support both of them. A police commissioner uses this knowledge to blackmail Bello into acting as an informer for him.

When a high-ranking Nazi is murdered due to jealousy between different pimps, the crime is blamed on the communists. Bello is supposed to be the star witness in the case, but he refuses to testify. When the Nazis come to power, they revive the case in order to make the murdered man into a martyr. Because Frieda is now of age, Bello mistakenly believes he is out of danger...