With it's plot of several English travellers on a train caught up in a foreign power's espionage in Europe on the brink of war, it speaks of it's time: when the passengers are finally confronted with the real threat facing them, they have to stand and fight.
Hitchcock's superb direction, Launder and Gilliat's cracking script and memorable performances make this a classic to enjoy again and again.
Shelf or charity shop? It's no mystery... Shelf!