An engineer leads the building of a trans-Atlantic tunnel linking Britain and the United States.

Richard Hanney has a rude awakening when a glamorous female spy falls into his bed - with a knife in her back. Having a bit of trouble explaining it all to Scotland Yard, he heads for the hills of Scotland to try to clear his name by locating the spy ring known as The 39 Steps.

'1670. Irish patriot caught stealing Crown Jewels talks his way to pardon.' (British Film Catalogue)