Set in a rundown sanatorium, this adaptation of Egon Hostowsky's novel Midnight Patient turns around the efforts of competing Soviet and American agents to secure a top secret nuclear device. However, this proves a mere MacGuffin, as Curt Jurgens, Sam Jaffe and Peter Ustinov manoeuvre for the kill.
This isn't in the same class as Les Diaboliques, but Henri-Georges Clouzot pulls off the same trick of repeatedly luring the audience into believing we've seen through the sleight of hand, only to discover that yet another character is not what they appear and that the guessing has to begin all over again.