Filmed in 1955, Les Espions (The Spies) was based on Midnight Patient, a novel by Egon Hostowsky. The scene is a rundown sanitarium, which is subtly but thoroughly taken over by a ruthless gang of international spies. One of the new "patients" is purportedly the inventor of a new nuclear explosive device, which of course attracts the attention of Russian and American counterspies. When it turns out that the inventor is a phony, it throws the entires espionage community into a frenzy. Before long, it is impossible to tell the good guys from the bad. As confusing as it sounds, Les Espions has the advantage of a superb international cast, including Curt Jurgens, Sam Jaffe, and Peter Ustinov.
~ Hal Erickson, All Movie Guide