Highly Dangerous is a 1950 British spy film starring Margaret Lockwood and Dane Clark.

It was directed by Roy Ward Baker, based on a screenplay and novel The Dark Frontier written by Eric Ambler.

Ambler had recently specialised in melodramas, but Highly Dangerous was a comedy thriller in the vein of Lockwood's earlier hits, The Lady Vanishes and Night Train to Munich.

[5] He added " Eric had invented a language for the people the other side of the curtain which wasn’t Russian or anything else and the poor actors had to learn this stuff.

Wendell Corey was originally sought[8] before the role was given to Dane Clark, who had recently left Warner Bros. "He was just delivering a stock leading man movie performance which was virtually nothing," said Baker.

I realised I’d been trying to piece it together in a logical way, sticking to the topography of Trieste I’d done myself an injury because the audience doesn't give a damn.