Paul Kranz, the manager of a TEE that had just arrived from Hamburg, received terrible news in Paris. His wife Ruth is in a coma after a serious traffic accident. Mr. Kranz will return immediately. He finds an unknown key in his wife's purse. It belongs to an apartment where Ruth, obviously with someone else, has led a strange double life as a call girl. In his shame and disappointment, Kranz allows himself to be carried away into a knee-jerk action. This is how a crime happens without intention.