All long the shooting, every member of the crew - technicians, screen player and actors - ignored how the film was about to end, nor who was the real evil character of the movie.
The movie was originally to be directed by Andrzej Zulawski. Zulawski left the project after dissensions between him and Lino Ventura.
Bruno Cremer plays a secret agent named Alain Richard. And nearly twenty years later, a French politician also called Alain Richard was appointed Minister of Defense - from whom secret agents depend (DGSE), the French Intelligence Service.