If this cold war comedy thriller feels like a reboot of those pre-war adventures about political intrigue in the Balkans, then that's what it is. Eric Ambler updates his 1936 debut novel to make the Communists the unnamed enemy. Margaret Lockwood is the unmarried, middle aged entomologist enlisted to investigate the use of bugs in chemical warfare.
So Lockwood is back in the Balkans, 12 years after The Lady Vanishes. She had planned on Torquay. Everything about this espionage caper is familiar, but still fun. When the bookish spinster gets pumped full of truth drug, she starts to imagine she is a spy superhero and breaks into the Reds' research centre to steal some enemy insects...
So it gets a bit silly. And the idiotic propaganda in the later scenes is disappointing. Dane Clark as the token American doesn't have much to offer and there is zero romantic chemistry. But Lockwood reliably carries the slender plot. This was developed as a vehicle for her- she has a new look- but her big screen career was winding down.
It's the sort of story that years earlier would have featured Charters and Caldicott, so it's a nice touch when Naunton Wayne turns up in a small part. Sure, it's all been done better before, especially by Eric Ambler, but it's a resilient genre and the formula works again, and the theme of germ warfare had some topicality.