After a chest is brought up from the bottom of an Austrian lake, the diver, Richard Bryant (Patrick Jordan), is found murdered. Bill Mathison (Barry Newman) is an American lawyer on vacation in Austria. He stops by a photography shop to meet with a man who is compiling a book of photographs of Austrian Lakes, as a favor to the publisher, and meets the photographer's wife Anna (Anna Karina). The photographer has disappeared. Mathison gets caught up in trying to find the chest recovered by Bryant. It is revealed to contain a list of former members of the Nazi party who could be embarrassingly connected to current United States politics.