The young lawyer Felix Spaet is one of many witnesses when a distinguished Zurich councilman, Dr. Isaak Kohler, shoots Professor Winter in the middle of a restaurant full of well-known politicians, businessmen and artists. Kohler is arrested and sentenced to 20 years imprisonment.
Dr. Kohler, happy as a lark and infectiously content behind bars, sends for Felix Spaet and asks him to re-investigate his case on the supposition that he is innocent. Down on his luck and out of money, Spaet has no alternative but to accept the job. The lawyer becomes obsessed with his intellectual enterprise and in the process he is driven to madness.
Source: German films Service & Marketing GmbH