.......sixteen years before Hitchcock's film was released .
And ,which was not derivative for the time , they reverse the genres : Margaret Lockwood is the scientist ,on a mission which is deemed "highly dangerous" ;the male lead being just an attentive escort ; it's typically "cold war" movie, depicting the Reds as villains ,but shrewd villains: "we know that torture won't make it ,for the prisoner can say anything to avoid sufferings ;so a simple injection will do". The truth drug is efficient ,in its own special way : Lockwood begins to be delirious and does some kind of self-criticism : without her nephew's radio serial -very popular in the fifties,few people had TV sets in Europa -, and the boy's hero ,agent Conway, she would perhaps have opted for her holiday in Torquay :hence the ironical passport!
No matter what the "Mcguffin " is: the most important thing is the feminist side of the movie,ahead of its time ;and
Lockwood's portrait of a determined woman is convincing.