Classic drama about the smashing of a Nazi spy ring operating in the U.S. Thanks to covert surveillance, the FBI learns of the presence of several suspicious persons in New York. Bill Dietrich (William Eythe) is a German-American college student approached by the spies to become a secret Nazi operative. Dietrich instead heads directly to FBI chief George A. Briggs (Lloyd Nolan) and offers his services as a double agent. His mission is to locate the head of the spy ring, an unseen figure known only as Mr. Christopher, and to that end Eythe infiltrates the ring, headquarted in a town house on 92nd street. Among the conspirators are an erudite German colonel, Col. Hammersohn (Leo G. Carroll) and the beautiful female owner of the house, Elsa Gebhardt (Signe Hasso).