A grounded American fighter pilot is switched to espionage on a special job in which he must kill a small-time Paris lawyer suspected of double-crossing France by selling out radio operators to the Nazis.

Claustrophobic train-set comedy-thriller (produced by H.G. Wells son) with an ace reporter coming up against crooks intent on stealing a gold shipment on the Scotland to London express. A scatterbrained scientist, a gun-toting dame with revenge on her mind and a pair of eccentric spinster crime novelists – who steal the film – round out the motley band of passengers who cross the path of our intrepid hero as he tries to get his big scoop.